Glossary
Healthcare AI glossary.
Plain-language definitions for the terms behind quality, compliance, and outreach, from HEDIS and PDC to the BAA and TCPA.
Core terms
- AI medical answering serviceAn AI medical answering service answers an organization's calls automatically, 24/7. It handles routine questions, captures the reason for the call, and routes anything urgent or clinical to a person. Unlike a traditional answering service that relays messages for staff to action later, it responds in real time and must operate under a signed HIPAA BAA.
- AI receptionistAn AI receptionist is software that answers inbound calls in natural language, works out why the caller is reaching out, and handles it: answering routine questions, capturing the request, and getting the caller to the right person. Unlike voicemail or a phone tree, it responds in real time, at any hour, and handles many calls at once.
- AI voice agentAn AI voice agent is software that holds a real spoken conversation over the phone: it answers or places calls, understands natural speech, replies in a lifelike voice, and takes action such as confirming a refill or transferring the caller. In healthcare it must run under a HIPAA BAA, and under the TCPA its voice counts as an artificial voice.
- Business Associate Agreement (BAA)A Business Associate Agreement (BAA) is a HIPAA-required contract between a covered entity, such as a medical practice or pharmacy, and any vendor that creates, receives, stores, or transmits protected health information on its behalf. It binds the vendor to safeguard that data, report breaches, and flow the same terms to its subcontractors.
- HIPAA-compliant AIHIPAA-compliant AI is AI software that can lawfully process protected health information. That requires two things: the vendor signs a Business Associate Agreement (BAA) covering the specific plan and features you use, and the system runs with HIPAA safeguards. Without a signed BAA, putting real patient data into an AI tool is not compliant, regardless of the model.
- Patient engagement automationPatient engagement automation is the use of software to run patient communication and outreach at scale: appointment reminders, screening recalls, refill and adherence outreach, intake, and inbound call handling, over voice, text, and web. Done well, it holds two-way conversations, honors opt-out, routes clinical issues to people, and records every outcome where staff can see it.
Programs and measures
- ACO REACHACO REACH (Accountable Care Organization Realizing Equity, Access, and Community Health) is a CMS Innovation Center model in which groups of doctors and other providers take responsibility for the total cost and quality of care for an aligned group of people with Original Medicare, and share in savings or losses. It is still active. CMS says its first performance year began January 1, 2023, and the model runs for four performance years, 2023 through 2026. Performance year 2026 is the final year, and CMS is not taking new applications for the rest of the model. CMS names the LEAD model as the successor. LEAD is announced and runs from January 1, 2027, through December 31, 2036.
- Adverse-event intakeAdverse-event intake is the operational path from a patient mentioning a safety signal to a named person receiving a transcribed, time-stamped report inside the program's reporting window. It is not diagnosis. It is detection, documentation, and routing so pharmacovigilance and clinical teams can act. Every voice, text, and chat path has to do this the same way.
- Annual Wellness Visit (AWV)The Annual Wellness Visit (AWV) is a yearly Medicare Part B benefit focused on prevention: the clinician builds or updates a personalized prevention plan, reviews health risks, screens for cognitive impairment and depression, and sets a screening schedule. It is not a head-to-toe physical, and it has no cost-sharing when the provider accepts assignment.
- Clinical trial recruitmentClinical trial recruitment is the process of identifying eligible patients, reaching them inside a clinical window, confirming interest and eligibility, and coordinating the next site or navigator step. Matching finds who qualifies. Recruitment is the conversation that turns a match into a consented, scheduled participant. In oncology, that conversation is where most eligible adults are lost.
- HEDISHEDIS (the Healthcare Effectiveness Data and Information Set) is a standardized set of performance measures, maintained by NCQA, that most US health plans use to report quality of care. It tracks things like cancer screenings, diabetes and blood-pressure control, and immunizations. Results feed Medicare Star Ratings and value-based contracts, so open HEDIS gaps carry real money.
- Medicare Shared Savings Program (MSSP)The Medicare Shared Savings Program (MSSP) is CMS's permanent accountable care program. An Accountable Care Organization (ACO) is accountable for the cost and quality of care for assigned Medicare fee-for-service beneficiaries. CMS uses two tracks, BASIC and ENHANCED. If spending is under the benchmark and quality standards are met, the ACO shares in the savings. Two-sided participation also shares losses.
- Medicare Star RatingsMedicare Star Ratings are CMS scores, from 1 to 5 stars, for Medicare Advantage and Part D plans. They combine dozens of measures of clinical quality, member experience, medication adherence, and customer service. Plans rated 4 stars or higher earn quality bonus payments, which KFF estimates at least $13.4 billion in 2026, so plans manage the measures all year.
- Medication Therapy Management (MTM)Medication Therapy Management (MTM) is a service, usually pharmacist-led, that reviews a patient's full medication regimen to improve safety, adherence, and outcomes. Medicare Part D plans must offer MTM to members who meet targeting criteria based on chronic conditions, number of drugs, and annual drug cost. Its centerpiece is the Comprehensive Medication Review (CMR).
- Patient support program (PSP)A patient support program, often run through a hub, is the brand-funded service that reaches referred patients, confirms eligibility and benefits, enrolls them, and follows them through first fills and persistence check-ins. The program fails when the referred patient is never reached, or when the hub, pharmacy, and site each restart the same case.
- Proportion of Days Covered (PDC)PDC is the medical abbreviation for Proportion of Days Covered, the standard measure of medication adherence. It is the percentage of days, from a patient's first fill to the end of the measurement period, that they had the medication on hand based on pharmacy claims. A PDC of 80% or higher is the usual adherence line for most chronic medications.
- TCPA (Telephone Consumer Protection Act)The Telephone Consumer Protection Act (TCPA) is the US federal law governing autodialed, prerecorded, and artificial-voice calls and texts. It sets consent rules, calling hours (8 a.m. to 9 p.m. local time), and opt-out obligations. Healthcare messages have specific exemptions with conditions. The FCC treats AI-generated voices as artificial voices, so the TCPA applies to AI calls.
Allowed AI at work
- Agentic AIAgentic AI describes AI systems that pursue a goal with some autonomy. They plan multistep work, use tools and data, take actions, check results, and adjust, with limited step-by-step human direction. It contrasts with generative AI used for a single prompt and response. In healthcare, agentic AI runs workflows such as patient outreach, intake, and follow-up.
- AI acceptable use policyAn AI acceptable use policy is a written set of rules for staff. It says which AI tools they may use at work, what data they may enter, and how AI output gets checked before use. In healthcare it names approved tools covered by a Business Associate Agreement, bars PHI in anything else, and assigns clear accountability.
- AI agentAn AI agent is software built on a language model that perceives its situation, decides what to do, and acts with tools. It works toward a goal rather than only producing text. In healthcare, an agent might read a care-gap list and call each patient. It answers their questions, logs outcomes, and hands off to staff when needed.
- AI hallucinationAn AI hallucination is output from a language model that sounds confident but is false, unsupported, or invented. Examples include a made-up citation, a wrong dosage, or a policy the organization never had. It happens because models predict plausible text rather than look up facts. In healthcare, hallucinations can mislead patients and staff, so outputs need grounding and review.
- Covered entity vs business associateUnder HIPAA, a covered entity is a health plan, a clearinghouse, or a provider that conducts standard electronic transactions such as claims. A business associate is a person or company that creates, receives, maintains, or transmits PHI on a covered entity's behalf. Both must follow HIPAA, and a Business Associate Agreement binds them.
- De-identification (HIPAA)De-identification is removing or altering identifiers so health information no longer identifies a person. At that point HIPAA no longer treats it as PHI. HIPAA allows two methods. Safe Harbor removes 18 specified identifiers, with no actual knowledge the rest could identify someone. In Expert Determination, a qualified expert finds re-identification risk very small.
- HIPAA Privacy RuleThe HIPAA Privacy Rule is the HHS regulation that limits how covered entities and their business associates use and disclose protected health information. It also gives people rights to see and receive a copy of that information. The text is 45 CFR Parts 160 and 164. This page is not legal advice. See the /glossary/protected-health-information entry.
- HIPAA Security RuleThe HIPAA Security Rule is the HHS regulation that requires safeguards for electronic protected health information. It covers administrative, physical, and technical safeguards. The text is 45 CFR Part 164, Subpart C. It applies to covered entities and to business associates. This page is not a security audit.
- HITRUSTHITRUST is a security and privacy assurance program run by the HITRUST Alliance. It is built on the HITRUST CSF, a control framework that maps HIPAA, NIST, ISO, and other standards into one set of requirements. Organizations earn HITRUST certification through validated assessments at three levels, e1, i1, and r2, each more rigorous than the last.
- Human-in-the-loop (HITL)Human-in-the-loop (HITL) is a design approach where a person reviews, approves, corrects, or takes over an AI system's work at defined points. The AI does not act fully on its own. In healthcare, HITL keeps clinicians and staff responsible for clinical judgment, sensitive actions, and exceptions, while AI handles the routine volume.
- Interactive voice response (IVR)Interactive voice response (IVR) is a phone system that greets callers with recorded prompts. It routes them through a menu using keypad presses or simple spoken words, such as 'press 1 for scheduling.' It handles routing and basic self-service, like refill requests by number. Unlike an AI voice agent, it does not understand open-ended requests.
- Minimum necessary standardThe minimum necessary standard is a HIPAA Privacy Rule requirement. Covered entities and business associates must make reasonable efforts to limit protected health information to what each use, disclosure, or request needs. It does not apply to disclosures for treatment, to the patient, under the patient's authorization, to HHS, or as required by law.
- Part 2 records42 CFR Part 2 is the federal rule that protects records of substance use disorder treatment from programs that receive federal assistance. Those records have consent and redisclosure limits that sit on top of HIPAA. A 2024 final rule aligned parts of Part 2 with HIPAA. This page is not a consent form.
- Protected health information (PHI)Protected health information (PHI) is individually identifiable health information that a HIPAA covered entity or business associate creates, receives, maintains, or transmits. It covers data about a person's health, care, or payment for care that could identify them. It applies in any form: electronic, paper, or spoken. Electronic PHI is called ePHI.
- Shadow AIShadow AI is the use of AI tools at work without the organization's approval or oversight. A common example is staff pasting patient lists into a personal ChatGPT account. In healthcare it creates HIPAA risk. Consumer AI tools usually come without a Business Associate Agreement, so patient data entered into them can be an impermissible disclosure.
- SOC 2 Type IISOC 2 Type II is an independent audit report issued by a CPA firm under AICPA standards. It tests whether a service organization's controls operated effectively over a period, usually 3 to 12 months. It measures controls against the AICPA Trust Services Criteria. It is an attestation report, not a certification, and it is not a HIPAA certification.
- Warm transferA warm transfer is a call handoff where the first party stays on until the next person is on the line. It passes along who is calling and why, so the caller does not repeat themselves. In a cold transfer, the call is simply sent to another line with no introduction. Warm transfers cut dropped calls and repeated questions.
- Zero data retention (ZDR)Zero data retention (ZDR) is an arrangement where an AI model provider does not store customer prompts or outputs after returning a response. Customers request it to limit how long sensitive data sits with the provider. ZDR is a contract and configuration setting. It is not a HIPAA requirement and does not replace a BAA.
Value-based care
- Advanced Primary Care Management (APCM)Advanced Primary Care Management (APCM) is a monthly Medicare care management service, effective January 1, 2025. It bundles care coordination into one per-month payment with no minimum time requirement. It is billed with HCPCS codes G0556, G0557, or G0558 based on the patient's chronic conditions and Qualified Medicare Beneficiary status. Patient consent is required.
- CapitationCapitation is a payment model that pays a provider a fixed amount per patient per month (PMPM) for a defined set of services. The amount stays the same however many services each patient uses. If care costs less than the payment, the provider keeps the difference. If it costs more, the provider absorbs the loss. Payments are usually risk-adjusted.
- Care gapA care gap is the difference between the care a patient should receive under guidelines or quality measures and the care they actually got. Common examples are an overdue mammogram, a missing A1c test, or a lapsed medication refill. Health plans and ACOs track open gaps because they drive quality scores, Star Ratings, and shared savings.
- Chronic Care Management (CCM)Chronic Care Management (CCM) is a Medicare service that pays for non-face-to-face care coordination. It covers patients with two or more chronic conditions expected to last at least 12 months. It requires documented patient consent, a comprehensive electronic care plan, and 24/7 access to care. It is billed monthly based on staff or practitioner time.
- Hierarchical Condition Category (HCC)A Hierarchical Condition Category (HCC) is a group of related diagnosis codes that CMS uses to predict a patient's future healthcare costs. Each HCC carries a weight, and within a disease family only the most severe category counts. HCCs feed the risk scores behind Medicare Advantage payments and ACO benchmarks. Payment year 2026 uses the V28 model.
- LEAD model (Long-term Enhanced ACO Design)The LEAD model (Long-term Enhanced ACO Design) is a voluntary CMS Innovation Center accountable care model. It runs from January 1, 2027 through December 31, 2036. ACOs choose Global Risk, sharing up to 100% of savings or losses, or Professional Risk, up to 50%. It offers capitated payments and a 10-year benchmark pathway without rebasing.
- Management services organization (MSO)A management services organization (MSO) is a company that provides non-clinical business services to physician practices. Examples include billing, payer contracting, credentialing, IT, staffing, and data analytics. The practice keeps clinical control while the MSO runs operations. MSOs are common in value-based care, where they help independent practices take on contracts and risk together.
- MIPS (Merit-based Incentive Payment System)The Merit-based Incentive Payment System (MIPS) is a Medicare Quality Payment Program track. It adjusts eligible clinicians' Part B payments based on a 0 to 100 performance score. The score combines Quality, Cost, Improvement Activities, and Promoting Interoperability. For the 2026 performance year, the threshold is 75 points and the maximum negative adjustment is -9%.
- Patient attributionPatient attribution is how a payer assigns patients to the provider, practice, or ACO accountable for their cost and quality of care. In the Medicare Shared Savings Program, CMS assigns beneficiaries mainly based on where they received the plurality of their primary care services. The attributed list defines whose outcomes count.
- Population health managementPopulation health management is the practice of improving outcomes across a defined group of patients. It uses data to find who needs care, stratify them by risk, and reach them proactively. Instead of waiting for patients to book, the care team works the whole panel. It closes care gaps, manages chronic conditions, and follows up after discharges.
- Remote patient monitoring (RPM)Remote patient monitoring (RPM) uses connected medical devices, such as blood pressure cuffs, glucometers, and scales, to collect a patient's physiologic data at home. The data goes to their care team. Clinicians review the readings and adjust treatment between visits. Medicare pays for RPM through device codes and monthly management codes.
- Risk adjustmentRisk adjustment is the method payers use to account for differences in patient health when setting payments or benchmarks. In Medicare, the CMS-HCC model turns each patient's demographics and documented diagnoses into a risk score. Sicker populations get higher expected costs, so plans and providers caring for complex patients are not penalized for it.
- Risk adjustment factor (RAF) scoreA risk adjustment factor (RAF) score is a number that estimates how costly a patient is expected to be. The average Medicare beneficiary scores about 1.0. CMS calculates it by adding demographic factors such as age, sex, and Medicaid status to the weights of the patient's documented HCCs. Higher scores mean higher expected costs.
- Transitional Care Management (TCM)Transitional Care Management (TCM) is a Medicare service covering the 30 days after a patient leaves a hospital, skilled nursing facility, or similar setting. It requires interactive contact with the patient or caregiver within 2 business days and a face-to-face visit within 7 or 14 days. It is billed with CPT 99495 or 99496.
- Value-based careValue-based care is a payment approach that rewards healthcare providers for patient outcomes, quality, and total cost of care. It does not pay for the number of services billed. Providers take accountability for a defined patient population through models such as shared savings, bundled payments, and capitation. They earn more when patients stay healthier at lower cost.
Pharmacy, Medicare enrollment, and access
- ADT notificationAn ADT notification is an electronic alert a hospital sends when a patient is admitted, discharged, or transferred. Medicare rules at 42 CFR 482.24(d) require hospitals with qualifying electronic records systems to send them. Recipients include the patient's primary care practitioner or group and post-acute providers. Practices use them to start transitional care outreach.
- Annual Enrollment Period (AEP)The Annual Enrollment Period (AEP) is the yearly Medicare window, October 15 to December 7, for changing Medicare Advantage and Part D coverage. Beneficiaries can join, switch, or drop plans, or move between Original Medicare and Medicare Advantage. Changes take effect January 1. Medicare.gov calls it Open Enrollment, while brokers and plans usually say AEP.
- Benefits investigation (BI)A benefits investigation (BI) is the process of verifying a patient's insurance coverage for a prescribed therapy. A patient support hub or specialty pharmacy confirms whether the drug is covered and whether prior authorization is needed. It also checks the copay or coinsurance and in-network specialty pharmacies. It is usually the first step in a support case.
- CAHPSCAHPS (Consumer Assessment of Healthcare Providers and Systems) is a family of standardized surveys that ask patients about their experience of care. The Agency for Healthcare Research and Quality oversees it. Medicare uses CAHPS results in Medicare Advantage and Part D Star Ratings, hospital programs, and ACO quality scoring, so experience scores affect payment.
- Comprehensive Medication Review (CMR)A Comprehensive Medication Review (CMR) is an interactive, one-on-one review of all of a patient's medications, usually done by a pharmacist. It is the core service of Medicare Part D Medication Therapy Management. It ends with a written summary, an action plan, and a medication list. Part D plans must offer one to MTM-enrolled members at least once a year.
- DIR feesDIR fees (direct and indirect remuneration) are price concessions Medicare Part D plans and their pharmacy benefit managers collect from network pharmacies. They are often tied to performance scores. Since January 1, 2024, CMS rule CMS-4192-F requires plans to apply all pharmacy price concessions at the point of sale. The pharmacy now knows its payment when it fills.
- Dual Eligible Special Needs Plan (D-SNP)A Dual Eligible Special Needs Plan (D-SNP) is a Medicare Advantage plan only for people who have both Medicare and Medicaid. It covers Medicare benefits and coordinates with the person's state Medicaid program. Every D-SNP must hold a contract with the state Medicaid agency, and some fully integrate Medicare and Medicaid benefits under one plan.
- Medicare Advantage Open Enrollment Period (OEP)The Medicare Advantage Open Enrollment Period (OEP) runs January 1 to March 31 each year. People already in a Medicare Advantage plan can make one change. They can switch to another Medicare Advantage plan, or drop to Original Medicare and add a Part D drug plan. The change takes effect the first day of the following month.
- Medicare Prescription Payment PlanThe Medicare Prescription Payment Plan is a free Part D option. Enrollees pay their out-of-pocket drug costs to their plan in monthly installments instead of all at once at the pharmacy. It does not lower total costs. It spreads them across the year, up to the Part D out-of-pocket cap of $2,100 in 2026 and $2,400 in 2027.
- Medication synchronization (med sync)Medication synchronization (med sync) is a pharmacy service that aligns all of a patient's chronic prescriptions to refill on the same day each month. The pharmacy short-fills some medications once to line them up, then contacts the patient before each sync date to confirm changes. The goal is fewer trips, fewer gaps, and better adherence.
- Prior authorization (PA)Prior authorization (PA) means a provider must get a health plan's approval before a service, procedure, or drug is covered. Under CMS rule CMS-0057-F, Medicare Advantage, Medicaid, and CHIP payers face deadlines starting in 2026. They must decide expedited requests within 72 hours and standard requests within 7 calendar days.
- Special Enrollment Period (SEP)A Special Enrollment Period (SEP) is a window outside the regular Medicare enrollment periods. It lets a beneficiary join, switch, or drop a Medicare Advantage or Part D plan after a qualifying event. Common triggers include moving out of a plan's service area, losing employer or other coverage, and a plan earning a 5-star rating.
- Third-party marketing organization (TPMO)A third-party marketing organization (TPMO) is an organization or individual paid to market or sell Medicare Advantage or Part D plans on a plan's behalf. Examples include agents, brokers, field marketing organizations, and call centers. CMS holds TPMOs to specific rules on disclaimers, call recording, consent to share data, and unsolicited contact.
- Turning 65 (T65)Turning 65 (T65) refers to people approaching their 65th birthday and first Medicare eligibility. Their Initial Enrollment Period lasts 7 months: the 3 months before their birthday month, that month, and the 3 months after. Brokers focus on T65 because these people are choosing coverage for the first time, often with guaranteed Medigap rights.
Provider identifiers and enrollment
- Authorized officialAn authorized official is the person an organization names who can act for it on the NPI application or the Medicare enrollment. On a Type 2 NPI the public record can list that person's name and title. That person may also have their own Type 1 NPI, which is a different number. Use the /npi-lookup.
- CAQHCAQH ProView is a central profile that physicians and other providers can keep so health plans can read the same credentialing data. It is run by CAQH, not by CMS. It is not the NPI registry and not PECOS. A plan may still ask for documents the profile does not hold.
- CredentialingCredentialing is the review a health plan or hospital does before a provider joins its network or medical staff. It usually checks the license, the NPI, malpractice history, and Medicare enrollment. This site can show the public NPI and a public enrollment row. It does not credential anyone. Use the /npi-lookup.
- Deactivated NPIA deactivated NPI is a number NPPES has turned off. The file records a deactivation date and a reason code. A later reactivation date means it was turned back on. This site treats a record as active when there is no deactivation date, or when reactivation is on or after deactivation. Use the /npi-lookup.
- Medicare opt-outA Medicare opt-out is an affidavit from a physician or practitioner who chooses not to bill Medicare for two years. CMS publishes the affidavits with the NPI, specialty, state, and effective dates. This site looks up one NPI at a time in that public file. Use the /medicare-opt-out-lookup.
- Medicare revalidationMedicare revalidation is the process that asks an enrolled provider or supplier to confirm that the PECOS record is still accurate. CMS sets the cycle, often every five years, and sooner in some cases. Missing the due date can lead to a deactivation of billing privileges. Use the /medicare-enrollment-lookup.
- National Provider IdentifierA National Provider Identifier is the 10-digit number CMS issues to a health care provider through NPPES. The tenth digit is a check digit. Type 1 is an individual. Type 2 is an organization. The public registry is npiregistry.cms.hhs.gov. NPI record pages on this site read that public registry and show the date of the read.
- NPI check digitThe tenth digit of an NPI is a check digit. CMS computes it with the Luhn formula, after prefixing the nine-digit identifier with 80840. A failed check means the number was typed wrong. It does not mean the NPI is deactivated or excluded. Use the /npi-lookup.
- NPI reactivationNPI reactivation is the date NPPES turns a deactivated number back on. The October 12, 2026 dissemination file has a deactivation date and a reactivation date. This site treats the record as active when the reactivation date is on or after the deactivation date. A reactivation is not a new NPI. Use the /npi-lookup.
- NPPESNPPES is the National Plan and Provider Enumeration System. CMS uses it to assign National Provider Identifiers and to publish the public registry. The monthly file dated October 12, 2026 is the V2 dissemination file. NPI record pages on this site read the public registry and show the date of the read. City and specialty counts come from the monthly file. Rivvi is not the CMS registry. Use the /npi-lookup.
- OIG LEIEThe List of Excluded Individuals and Entities is the public HHS file of exclusions from Medicare, Medicaid, and other federal health programs. This site stores NPI numbers from that file and no names. The file is the September 2026 update, last modified October 9, 2026. OIG's own search is the check that counts. Use the /oig-exclusion-check.
- Ordering and referringEligible to order and refer means the NPI is on the CMS file of providers whose orders and referrals Medicare will accept. The Medicare opt-out file also carries this flag. An opt-out does not by itself remove the flag. Use the /medicare-opt-out-lookup.
- PECOSPECOS is the Provider Enrollment, Chain, and Ownership System. Medicare providers and suppliers use it to enroll, revalidate, and update their enrollment. A public CMS dataset reports enrollment rows by NPI. A missing row on a lookup page is not a decision that someone is unenrolled. Use the /medicare-enrollment-lookup.
- Primary taxonomyThe primary taxonomy is the specialty an NPI record marks with the primary switch. The October 12, 2026 NPPES file allows up to 15 taxonomy codes. When the switch is Y, that code is primary. When no switch is Y, this site's hub counts use the first code on the row. Use the /npi-lookup.
- Referring providerThe referring provider is the physician or practitioner who referred the patient for the service on a claim. Medicare asks for that NPI on many claims, and the NPI has to be eligible to order and refer. The public opt-out file carries that flag. Use the /medicare-opt-out-lookup.
- Rendering providerThe rendering provider is the individual who performed the service reported on a claim. On a professional claim the rendering provider's NPI is usually a Type 1 NPI. The billing provider can be a different organization with a Type 2 NPI. This site looks up either number. Use the /npi-lookup.
- Taxonomy codeA health care provider taxonomy code is the 10-character code on an NPI record that states a specialty or service type. NUCC maintains the code set. This site shows the short description the NPPES record itself carries, such as Family Medicine. It does not print NUCC definition paragraphs. Use the /npi-lookup.
- Type 1 NPIA Type 1 NPI is the National Provider Identifier for an individual person, such as a physician, nurse, or therapist. It stays with that person when they change jobs. A Type 2 NPI is for an organization. Both are 10 digits, and the tenth digit is a check digit. Use the /npi-lookup.
- Type 2 NPIA Type 2 NPI is the National Provider Identifier for an organization, such as a hospital, group, or supplier. It is not the personal identifier of a clinician who works there. In the NPPES file, entity type 2 is the organization. Use the /npi-lookup.
Codes and claim data
- 11-digit NDCThe 11-digit NDC is the form payers use on claims. FDA prints the code in 10-digit segments. The 11-digit form inserts a leading zero so the labeler, product, and package segments are 5, 4, and 2 digits. The ASP crosswalk uses the 11-digit form. Use the /ndc.
- Billable codeA billable ICD-10-CM code is a code the CDC order file marks as valid to report on a claim. A header code groups more specific codes and is not billable. The FY2027 order file dated June 16, 2026 has 74,879 billable codes out of 98,403 codes. Use the /icd-10.
- Complication or comorbidityA complication or comorbidity, and a major complication or comorbidity, are secondary diagnoses that can move an inpatient stay into a higher-paying MS-DRG. CMS lists them in the IPPS tables. The FY2027 Table 5 on this site shows the group title and weight, not the CC list itself. Use the /drg.
- Excludes1An Excludes1 note in ICD-10-CM is a pure excludes note. CDC says it means the excluded condition is not coded with the code above the note, because the two conditions cannot occur together. This site prints the note from the FY2027 tabular file. It does not tell you which code to submit. Use the /icd-10.
- Excludes2An Excludes2 note in ICD-10-CM means the excluded condition is not part of the code above the note. CDC says both conditions can be reported together when both are present. This site prints the note from the FY2027 tabular file dated June 16, 2026. It does not tell you which code to submit. Use the /icd-10.
- HCPCS Level IIHCPCS Level II codes are CMS alphanumeric codes for products, supplies, and services that are not CPT codes. The October 2026 file is dated September 23, 2026. This site lists Level II codes and Level II modifiers. It does not list CPT descriptors or CPT modifiers. Those are copyrighted by the AMA.
- HCPCS modifierAn HCPCS modifier is a two-character code that adds detail to a procedure or service code. Level II modifiers come from the CMS quarterly file. This site lists 384 of them from the October 2026 file dated September 23, 2026. Modifier AA is anesthesia performed personally by the anesthesiologist. Use the /hcpcs/modifiers.
- Header codeA header code in ICD-10-CM groups more specific codes under a category or subcategory. The order file does not mark it billable, so it is not reported alone on a claim. The more specific child codes are the ones the file marks billable. Use the /icd-10.
- ICD-10-CMICD-10-CM is the US clinical modification of the International Classification of Diseases, 10th revision. CDC's National Center for Health Statistics publishes the code set. FY2027 files are dated June 16, 2026. A header code groups more specific codes. A billable code can stand on a claim.
- J codeJ codes are HCPCS Level II codes in the J section. CMS uses them for many drugs that are not taken by mouth. The October 2026 file is dated September 23, 2026. When the ASP crosswalk lists NDCs, the code page shows those NDCs and the billable units. Use the /hcpcs/j-codes.
- Labeler codeThe labeler code is the first segment of a National Drug Code. FDA assigns it to the firm that manufactures, repacks, or distributes the drug under its own name. The product and package segments come after it. On an HCPCS crosswalk row, this site shows the labeler next to the drug name. Use the /ndc.
- Major diagnostic categoryA major diagnostic category (MDC) is the broad body-system group that contains a set of MS-DRGs. Table 5 of the FY2027 IPPS (inpatient prospective payment system) correction notice lists the MDC next to the group when the file has one. Pre-MDC groups, including transplants and tracheostomy, sit outside a single body system. Use the /drg.
- Modifier 25Modifier 25 reports a significant, separately identifiable evaluation and management service by the same physician on the same day as a procedure or other service. It is a CPT modifier. This site does not publish the CPT descriptor text. It is not an HCPCS Level II modifier. Use the /hcpcs/modifiers.
- Modifier 95Modifier 95 means a synchronous telehealth service was rendered via a real-time interactive audio and video system. It is a CPT modifier that CMS also recognizes. It is not a place of service code. Place of service 02 or 10 says where the patient was. Use the /place-of-service-codes.
- MS-DRGAn MS-DRG is a Medicare Severity Diagnosis Related Group. Medicare groups an inpatient stay into one of these groups and pays the hospital from the group's relative weight. The FY2027 correction notice lists 768 groups. This site copies Table 5 from CMS-1849-CN, dated September 23, 2026. Use the /drg.
- MS-DRG relative weightThe MS-DRG relative weight compares the average cost of one inpatient group with the average cost of all groups. A weight above 1 is costlier than average. The FY2027 correction notice lists the weights in Table 5, dated September 23, 2026. Groups 998 and 999 have no weight. Use the /drg.
- National Drug CodeA National Drug Code is the number FDA assigns to a drug product. The 11-digit form identifies the labeler, the product, and the package. FDA updates the directory as products change. This site reads the public openFDA NDC directory when you search. Use the /ndc.
- Place of serviceA place of service code tells a payer where a professional health care service happened. CMS publishes the code set for professional claims. Code 11 is an office. Code 02 is telehealth provided somewhere other than the patient's home. This site copies the CMS file dated May 2, 2024. Use the /place-of-service-codes.
- Present on admissionA present on admission indicator on an inpatient claim says whether a diagnosis was present when the patient was admitted. CMS uses it so a hospital is not paid extra for a condition that developed after admission in specified cases. It is not part of the ICD-10-CM code itself. Use the /icd-10.
- Quantity limitA quantity limit is the maximum amount of a drug a plan will cover in a set period, such as a 30-day supply or a number of tablets. Medicare Part D plans publish these limits on their formularies. This site does not publish formulary pages, so it does not show a limit for a specific plan and drug.
- Step therapyStep therapy is a plan rule that asks a person to try a preferred drug before the plan covers a different drug for the same condition. It is a utilization management rule, like prior authorization and quantity limits. Medicare Part D plans can use it. This page does not say whether a plan applies it to a drug.
- Telehealth place of serviceCMS uses two place of service codes for telehealth. Code 02 is telehealth provided somewhere other than the patient's home. Code 10 is telehealth provided in the patient's home. The code set on this site is the CMS file dated May 2, 2024. Use the /place-of-service-codes.
- Type of billA type of bill is a four-character code on an institutional claim. It says the kind of facility, the kind of care, and whether the claim is an original, a replacement, or a void. It is not an MS-DRG and not a place of service. Use the /place-of-service-codes.
Medicare program and benefits
- Benefit periodA Medicare benefit period measures a spell of inpatient hospital and skilled nursing care. It starts on admission and ends after 60 days in a row with no inpatient hospital or skilled nursing care. A new period brings a new Part A deductible. This page does not track a person's days.
- C-SNPA C-SNP is a Chronic Condition Special Needs Plan. It is a Medicare Advantage plan that limits enrollment to people with a severe or disabling chronic condition that CMS allows for that plan. It is not a D-SNP and not an I-SNP. Star Ratings still apply to the contract. Use the /star-ratings-2027.
- CMS-HCCA CMS-HCC is a Hierarchical Condition Category in the Medicare Advantage risk model. CMS maps ICD-10-CM codes to category numbers. This site uses the 2027 initial mapping file. Codes added for FY2027 that have no row say that no mapping is published yet. Use the /icd-10.
- Dual eligibleA dual eligible person qualifies for Medicare and for Medicaid. Medicare is usually primary for Medicare-covered services. Medicaid may help with premiums, cost sharing, or services Medicare does not cover. A D-SNP is a Medicare Advantage plan built for this group. See the /glossary/d-snp entry.
- Extra HelpExtra Help, also called the Low Income Subsidy, lowers Part D premiums, deductibles, and drug costs for people who qualify by income and resources. Social Security and Medicaid take applications. It is not the Medicare Prescription Payment Plan, which spreads costs across the year for people who do not get Extra Help.
- Fee-for-serviceMedicare fee-for-service is Original Medicare paying a covered claim as it is submitted. A Medicare Administrative Contractor processes the claim. Medicare Advantage is different: the plan receives a monthly payment and pays its own claims. Star Ratings score those plans, not fee-for-service. Use the /star-ratings-2027.
- I-SNPAn I-SNP is an Institutional Special Needs Plan. It is a Medicare Advantage plan for people who live in an institution, or who live in the community and need the level of care an institution provides. It is not a D-SNP and not a C-SNP. Use the /star-ratings-2027.
- Limiting chargeThe limiting charge is the cap on what a nonparticipating provider who does not accept assignment may collect for a Medicare-covered service. Medicare sets it at 115 percent of the nonparticipating fee schedule amount. It does not apply when the provider accepts assignment. This page does not compute a charge.
- Medicare AdvantageMedicare Advantage is Medicare Part C. A private plan contracts with Medicare to cover Part A and Part B benefits, and many plans include Part D drugs. CMS publishes Star Ratings for the contracts. The 2027 ratings were released October 8, 2026. Plan enrollment for the next year runs October 15 through December 7. Use the /star-ratings-2027.
- Medicare assignmentMedicare assignment means a provider agrees to accept the Medicare-approved amount as full payment for a covered service. Participating providers always accept assignment. A nonparticipating provider may accept it on a claim by claim basis. This page does not say whether a given NPI accepts assignment. Use the /npi-lookup.
- Medicare Beneficiary IdentifierA Medicare Beneficiary Identifier is the 11-character number on a Medicare card. CMS replaced the old Health Insurance Claim Number, which was based on a Social Security number. An MBI identifies the person. An NPI identifies the provider. This site does not look up MBIs and does not store them.
- Medicare Part AMedicare Part A is hospital insurance. It helps pay for inpatient hospital care, skilled nursing facility care after a qualifying stay, some home health, and hospice. It is part of Original Medicare. A Medicare Advantage plan must cover Part A benefits. Use the /drg.
- Medicare Part BMedicare Part B is medical insurance. It helps pay for physician services, outpatient care, and some drugs that are not taken by mouth. Many of those drugs are reported with HCPCS J codes. Part B is part of Original Medicare. Use the /hcpcs/j-codes.
- Medicare Part DMedicare Part D is outpatient prescription drug coverage. It can stand alone or sit inside a Medicare Advantage plan. CMS rates the drug portion of contracts in the Star Ratings. The 2027 ratings file separates Part C and Part D scores when the contract has them. Use the /star-ratings-2027.
- MedigapMedigap is Medicare supplement insurance. It helps pay deductibles, coinsurance, and copayments that Original Medicare leaves to the patient. It is not a Medicare Advantage plan. A person who joins Medicare Advantage generally cannot use a Medigap policy for the same coverage.
- Original MedicareOriginal Medicare is Part A hospital insurance and Part B medical insurance, paid by the federal program rather than a Medicare Advantage plan. People who want drug coverage add a Part D plan. People who want help with deductibles and coinsurance can buy a Medigap policy. Enrollment rules are on Medicare.gov.
- Qualified Medicare BeneficiaryA Qualified Medicare Beneficiary is a person in a Medicare Savings Program. Medicaid pays their Part A and Part B premiums and Medicare cost sharing if they meet the income and resource tests. Federal rules bar providers from billing a QMB individual for Medicare cost sharing. This page does not check eligibility.
- Quality bonus paymentA quality bonus payment is extra money Medicare pays a Medicare Advantage contract when its Star Rating qualifies. The 2027 Star Ratings, released October 8, 2026, affect 2028 quality bonus payments. They are not the bonus for 2027. Use the /star-ratings-2027.
Claims processing and coverage determinations
- Advance Beneficiary NoticeAn Advance Beneficiary Notice of Noncoverage is the CMS form a provider gives a Medicare patient before providing a service that Medicare may not cover. The patient can choose to get the service and accept possible payment responsibility. It is not a prior authorization and not a denial code. This site does not issue ABNs.
- Average sales priceAverage sales price is the manufacturer-reported price Medicare uses to pay many Part B drugs. CMS publishes a quarterly payment file and an NDC to HCPCS crosswalk. This site stores the October 2026 crosswalk, effective October 1, 2026 through December 31, 2026. It does not store the short descriptor, which can be CPT text. Use the /hcpcs.
- Coordination of benefitsCoordination of benefits is the set of rules that decides which payer pays first when a person has more than one plan. Medicare is sometimes primary and sometimes secondary, depending on the other coverage, such as an employer plan or Medicaid. This page does not decide the order for a person.
- Local Coverage DeterminationA Local Coverage Determination is a decision by a Medicare Administrative Contractor about whether an item or service is reasonable and necessary in that contractor's area. It is not a national rule. CMS posts LCDs in the Medicare Coverage Database. This page does not apply an LCD to a patient.
- Medicare Administrative ContractorA Medicare Administrative Contractor is a company CMS hires to process Medicare claims in a region. The contractor pays fee-for-service claims and can publish Local Coverage Determinations for its area. It is not a Medicare Advantage plan. See the /glossary/lcd entry.
- National Coverage DeterminationA National Coverage Determination is CMS's nationwide decision about whether Medicare covers an item or service. Contractors follow it. When no NCD exists, a contractor may publish an LCD. This page does not apply an NCD to a person or a claim.
- Open PaymentsOpen Payments is the CMS program that collects and publishes payments and other transfers of value from drug and device companies to physicians and teaching hospitals. It is required by the Sunshine Act. It is not the NPI registry and not an exclusion list. This site does not republish payment amounts.
- RedeterminationA redetermination is the first level of appeal for an Original Medicare claim. The Medicare Administrative Contractor that processed the claim reviews it again. A request is generally due within 120 days of receiving the initial determination. Later levels are reconsideration, an administrative law judge, the Medicare Appeals Council, and federal court.
- Remittance adviceA remittance advice is the statement a payer sends to explain how it processed a claim. Medicare's electronic version is the ERA, and the paper version is the SPR. It lists the billed amount, the allowed amount, and the adjustment reasons. This site does not store remittances and does not list denial reason codes.
- Timely filingMedicare timely filing is the deadline for a fee-for-service claim. For dates of service on or after January 1, 2010, the claim must be received within one calendar year of the date of service. A Medicare Advantage plan can set its own, shorter deadline in its contract. This page does not file claims.
Care settings and facility types
- Critical access hospitalA critical access hospital is a small hospital that Medicare designates, generally in a rural area, with 25 or fewer inpatient beds and a limit on the average length of stay. Medicare generally pays it 101 percent of reasonable cost rather than under the inpatient prospective payment system (IPPS). It has its own NPI. Use the /npi-lookup.
- Durable medical equipmentDurable medical equipment is equipment Medicare Part B can cover when it is durable, used for a medical reason, not useful to someone who is not sick or injured, and appropriate for use in the home. Examples include walkers and oxygen equipment. Suppliers have their own NPIs. Use the /npi-lookup.
- Federally qualified health centerA federally qualified health center is a clinic that meets Section 330 of the Public Health Service Act, or is treated as meeting it, and serves an underserved area. Medicare pays FQHCs under a prospective payment system, not the ordinary physician fee schedule. The clinic has its own NPI. Use the /npi-lookup.
- Home health benefitThe Medicare home health benefit covers part-time skilled nursing, therapy, and home health aide services for people who are homebound and need skilled care. A physician or allowed practitioner must certify the need. It is not round-the-clock custodial care. This page does not check eligibility.
- Hospice benefitThe Medicare hospice benefit covers care for a terminal illness when a person elects hospice and a physician certifies a life expectancy of six months or less if the illness runs its normal course. The election waives Medicare payment for curative care of that illness. This page does not start an election.
- Rural health clinicA rural health clinic is a clinic Medicare certifies in a rural area that is short of health professionals. Medicare pays an all-inclusive rate for a visit. The clinic must be staffed with a nurse practitioner, physician assistant, or certified nurse midwife at least half the time it is open. Use the /npi-lookup.
- Skilled nursing facilityA skilled nursing facility benefit under Medicare Part A covers skilled care after a qualifying inpatient hospital stay. Medicare measures the benefit in days of a benefit period, and coinsurance applies after the first 20 days. It is not long-term custodial care. This page does not check whether a stay qualifies.
Insurance and Medicare terms
160 terms defined from HealthCare.gov, Medicare.gov, CMS, and the IRS, with the figures and the source behind each one.
Most searched
- COBRA continuation coverage
- Coinsurance
- Copay (copayment)
- Deductible
- Explanation of benefits (EOB)
- Flexible spending account (FSA)
- Formulary
- Health maintenance organization (HMO)
- Health savings account (HSA)
- IRMAA (income-related monthly adjustment amount)
- Medicaid
- Medicare
- Medicare Part B deductible
- Medicare Part B premium
- Medigap Plan G
- Out-of-pocket maximum
- Part D out-of-pocket limit
- Pharmacy benefit manager (PBM)
- Preferred provider organization (PPO)
Programs
- Accountable care organization (ACO)
- Children's Health Insurance Program (CHIP)
- COBRA continuation coverage
- EPSDT
- Home and community-based services (HCBS)
- Medicaid
- Payment bundling
- State continuation coverage
- State Health Insurance Assistance Program (SHIP)
- TRICARE
- Uncompensated care
- Value-based purchasing (VBP)
- Workers' compensation
Costs
Accounts and tax
Drug coverage
Plan types
- Catastrophic health plan
- Dependent coverage
- Employer or union retiree plan
- Exclusive provider organization (EPO)
- Fully insured job-based plan
- Group health plan
- Health coverage
- Health maintenance organization (HMO)
- High deductible health plan (HDHP)
- Individual health insurance policy
- Job-based health plan
- Large group health plan
- Non-preferred provider
- Plan year
- Point of service (POS) plan
- Preferred provider
- Preferred provider organization (PPO)
- Provider network
- Rider
- Self-insured plan
- Stand-alone dental plan
- Summary of Benefits and Coverage (SBC)
- Waiting period
Medicare
- Creditable coverage
- Donut hole (Part D coverage gap)
- General Enrollment Period (GEP)
- Initial Enrollment Period (IEP)
- IRMAA (income-related monthly adjustment amount)
- Lifetime reserve days
- Medicare
- Medicare hospital insurance tax
- Medicare Part A deductible
- Medicare Part B deductible
- Medicare Part B premium
- Medicare Part C
- Medicare Savings Program (MSP)
- Medicare-approved amount
- Medigap Open Enrollment Period
- Medigap Plan F
- Medigap Plan G
- Medigap Plan N
- Part B excess charge
- Part B late enrollment penalty
- Part D deductible
- Part D late enrollment penalty
- Part D out-of-pocket limit
- Premium-free Part A
Marketplace
- Actuarial value
- Advance premium tax credit (APTC)
- Affordable Care Act (ACA)
- Bronze plan
- Certified application counselor
- Community rating
- Cost-sharing reduction (CSR)
- Employer shared responsibility payment (ESRP)
- Essential health benefits
- Federal poverty level (FPL)
- Gold plan
- Grandfathered health plan
- Guaranteed issue
- Guaranteed renewal
- Health insurance agent and broker
- Health Insurance Marketplace
- Marketplace Open Enrollment Period
- Marketplace quality ratings
- Medical loss ratio (MLR)
- Medical underwriting
- Metal levels (health plan categories)
- Minimum essential coverage (MEC)
- Minimum value
- Modified adjusted gross income (MAGI)
- Navigator
- Platinum plan
- Pre-existing condition
- Premium tax credit
- Qualified health plan (QHP)
- Qualifying life event (QLE)
- Rate review
- Reinsurance
- Second lowest cost Silver plan (SLCSP)
- Silver plan
- Small Business Health Options Program (SHOP)
- State insurance department
- Zero cost sharing plan
Care and services
- Benefits
- Care coordination
- Chronic disease management
- Dental coverage
- Emergency medical condition
- Emergency medical transportation
- Emergency room care
- Emergency services
- Excluded services
- Habilitative services
- Home health care
- Hospice services
- Hospital outpatient care
- Hospitalization
- Inpatient care
- Long-term care
- Medically necessary
- Physician services
- Preventive services
- Primary care provider (PCP)
- Referral
- Rehabilitative services
- Skilled nursing care
- Specialist
- Urgent care
- Vision coverage
- Well-baby and well-child visits
- Wellness program