Modifier GA
Waiver of liability statement issued as required by payer policy
Use it when
- A Medicare service expected to be denied as not reasonable and necessary
- Where a valid ABN was signed by the beneficiary before the service
- Where the practice intends to bill the patient after the denial
Do not use it when
- No ABN was obtained, or it was obtained after the service
- A blanket ABN signed routinely at registration, which is not valid
- Services excluded by statute rather than denied for medical necessity
A worked example
A chiropractic patient has reached maximum therapeutic benefit and further care is maintenance rather than active treatment. Maintenance is not a Medicare benefit.
Before the visit, the patient signs an ABN naming the service, stating the expected reason for non-coverage and an estimated cost, and selecting an option. The claim is submitted with modifier GA.
Medicare denies, as expected, and the denial notice establishes patient responsibility. Without modifier GA and a valid ABN, the balance would be written off entirely.
What decides it
The modifier is an attestation, not a formality. Appending GA where no valid notice exists is a false statement about the file, and the usage pattern is visible in claims data without anyone opening a chart.
ABN validity is where most of this fails. The notice must be issued before the service, identify the specific service, state the specific expected reason for denial, give an estimated cost, and carry a signature with an option selected. CMS treats routine blanket issuance as no issuance at all.
Related modifiers distinguish different situations. Where a notice was not obtained but the practice knows the service is non-covered, a different modifier applies, and it does not make the balance billable. Choosing between them is a judgement about what is actually in the file.
Denial codes this affects
Modifiers often confused with this one
Terms used here — Medical Necessity · Patient Responsibility · Denial
How we handle it — Denial Management · Patient Collections · Eligibility Verification
Every CPT and HCPCS modifier with a guide
Coverage attestation
- GAWaiver of Liability, ABN on File
- KXMedical Policy Requirements Met
Evaluation and management
Global period
Multiple and bilateral
Primary sources
What the payers and code-set maintainers actually publish about modifier GA.
- Advance Beneficiary Notice of Noncoverage (ABN) (opens in a new tab)
Centers for Medicare & Medicaid Services — The form and the rules for issuing it. Whether a non-covered service can be billed to the patient usually turns on whether a valid ABN was obtained beforehand.
- Medicare Coverage Database (LCD/NCD) (opens in a new tab)
Centers for Medicare & Medicaid Services — Searchable national and local coverage determinations. The direct answer to whether a diagnosis supports medical necessity for a given procedure.
Questions about modifier GA
That a valid Advance Beneficiary Notice is on file for a service expected to be denied as not medically necessary. It is what makes the balance billable to the patient once the denial arrives — without it, the balance is written off.
Issued before the service, naming the specific service, stating the specific expected reason for denial, giving an estimated cost, and signed with an option selected. A blanket notice signed routinely by every patient at registration is treated by CMS as no notice at all.
Only if a valid ABN was genuinely obtained before the service. The modifier attests to what is in the file; appending it where no valid notice exists is a false statement, and the pattern is visible in claims data.
No. It applies where a service is expected to be denied as not reasonable and necessary. Services excluded by statute are a different category, and an ABN is not the instrument that governs them.
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