HCPCS Level II modifier
Modifier GG
Modifier GG is a HCPCS Level II modifier. CMS describes it as: Performance and payment of a screening mammogram and diagnostic mammogram on the same patient, same day.
Source: CMS HCPCS Level II, October 2026 file dated September 23, 2026. Publisher page
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- Modifier
- GG
- Type
- HCPCS Level II modifier, maintained by CMS
- CMS description
- Performance and payment of a screening mammogram and diagnostic mammogram on the same patient, same day
- 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
- GHDiagnostic mammogram converted from screening mammogram on same day
- GFNon-physician (e.g. nurse practitioner (NP), certified registered nurse anesthetist (CRNA), certified registered nurse (CRN), clinical nurse specialist (CNS), physician assistant (PA)) services in a critical access hospital
- GJ"opt out" physician or practitioner emergency or urgent service
- GEThis service has been performed by a resident without the presence of a teaching physician under the primary care exception
- GKReasonable and necessary item/service associated with a ga or gz modifier
- GDUnits of service exceeds medically unlikely edit value and represents reasonable and necessary services
- GLMedically unnecessary upgrade provided instead of non-upgraded item, no charge, no advance beneficiary notice (ABN)
- GCThis service has been performed in part by a resident under the direction of a teaching physician
Related pages
Questions
What does modifier GG mean?
Modifier GG is a HCPCS Level II modifier. CMS describes it as: Performance and payment of a screening mammogram and diagnostic mammogram on the same patient, same day.
Is modifier GG a CPT or a HCPCS modifier?
GG 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 GG 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.