HCPCS Level II modifier
Modifier G8
Modifier G8 is a HCPCS Level II modifier. CMS describes it as: Monitored anesthesia care (MAC) for deep complex, complicated, or markedly invasive surgical procedure.
Source: CMS HCPCS Level II, October 2026 file dated September 23, 2026. Publisher page
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- Modifier
- G8
- Type
- HCPCS Level II modifier, maintained by CMS
- CMS description
- Monitored anesthesia care (MAC) for deep complex, complicated, or markedly invasive surgical procedure
- Claim form
- CMS-1500 item 24D, up to four modifiers per line. 837P SV101-3 to SV101-6.
- Guidance
- CMS HCPCS quarterly update
Anesthesia
- AAAnesthesia services performed personally by anesthesiologist
- ADMedical supervision by a physician: more than four concurrent anesthesia procedures
- QKMedical direction of two, three, or four concurrent anesthesia procedures involving qualified individuals
- QXCRNA service: with medical direction by a physician
- QYMedical direction of one certified registered nurse anesthetist (CRNA) by an anesthesiologist
- QZCRNA service: without medical direction by a physician
- QSMonitored anesthesia care service
- G9Monitored anesthesia care for patient who has history of severe cardio-pulmonary condition
- 23Unusual anesthesia
- 47Anesthesia by the surgeon
Related modifiers
- AAAnesthesia services performed personally by anesthesiologist
- ADMedical supervision by a physician: more than four concurrent anesthesia procedures
- QKMedical direction of two, three, or four concurrent anesthesia procedures involving qualified individuals
- QXCRNA service: with medical direction by a physician
- QYMedical direction of one certified registered nurse anesthetist (CRNA) by an anesthesiologist
- QZCRNA service: without medical direction by a physician
- QSMonitored anesthesia care service
- G9Monitored anesthesia care for patient who has history of severe cardio-pulmonary condition
- 23Unusual anesthesia
- 47Anesthesia by the surgeon
Related pages
Questions
What does modifier G8 mean?
Modifier G8 is a HCPCS Level II modifier. CMS describes it as: Monitored anesthesia care (MAC) for deep complex, complicated, or markedly invasive surgical procedure.
Is modifier G8 a CPT or a HCPCS modifier?
G8 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 G8 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.