HCPCS Level II modifier
Modifier AF
Modifier AF is a HCPCS Level II modifier. CMS describes it as: Specialty physician.
Source: CMS HCPCS Level II, October 2026 file dated September 23, 2026. Publisher page
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- Modifier
- AF
- Type
- HCPCS Level II modifier, maintained by CMS
- CMS description
- Specialty physician
- Claim form
- CMS-1500 item 24D, up to four modifiers per line. 837P SV101-3 to SV101-6.
- Guidance
- CMS HCPCS quarterly update
Related modifiers
- AGPrimary physician
- AERegistered dietician
- AHClinical psychologist
- ADMedical supervision by a physician: more than four concurrent anesthesia procedures
- AIPrincipal physician of record
- ACInitial onboarding support payment for access beneficiary enrollment, device/app setup, and care coordination activities; first month only; once per beneficiary per track
- AJClinical social worker
- ABAudiology service furnished personally by an audiologist without a physician/NPP order for non-acute hearing assessment unrelated to disequilibrium, or hearing aids, or examinations for the purpose of prescribing, fitting, or changing hearing aids; service may be performed once every 12 months, per beneficiary
Related pages
Questions
What does modifier AF mean?
Modifier AF is a HCPCS Level II modifier. CMS describes it as: Specialty physician.
Is modifier AF a CPT or a HCPCS modifier?
AF is a HCPCS Level II modifier from the CMS quarterly HCPCS file. Two-digit numeric modifiers, such as 25 or 59, are CPT modifiers.
Where does modifier AF go on a claim?
On the CMS-1500 it goes in item 24D next to the procedure code. Each line holds up to four modifiers. On an 837P it goes in SV101-3 to SV101-6.
What denial comes back when a modifier is wrong?
A missing or mismatched modifier often comes back as CARC 4. A modifier that was not valid on the date of service comes back as CARC 182. A bundling edit the modifier should have bypassed comes back as CARC 97 or 236.