GA

Overview

Modifier GA tells Medicare that the provider has issued a beneficiary an Advance Beneficiary Notice of Non-coverage (ABN) for a service the provider expects Medicare to deny as not reasonable and necessary. The signed ABN transfers financial liability to the beneficiary if Medicare denies the claim. GA is one of three ABN-related modifiers — GA, GY, and GZ — and choosing the correct one matters for both audit posture and patient billing.

When to use

• The provider believes Medicare will deny the service as not reasonable and necessary under §1862(a)(1) of the Social Security Act.
• A valid ABN (Form CMS-R-131) has been issued to the beneficiary before the service was rendered.
• The beneficiary has signed and dated the ABN, accepting financial liability if Medicare denies.

Common mistakes

• Using GA when the service is statutorily excluded — that requires GY, not GA.
• Failing to issue the ABN before the service is rendered. A post-service ABN is invalid and the provider remains liable.
• Using GA for non-Medicare payers — GA is a Medicare-specific modifier.

Examples

• E0250-GA — Hospital bed for a patient who does not meet LCD criteria; ABN signed before delivery acknowledging the patient may be financially responsible.
• L8499-GA — Prosthetic supply with uncertain coverage; ABN obtained because the provider expects denial as not reasonable and necessary.