G-Codes in Medicare: Functional Limitation Reporting

G-codes cover a wide array of services in HCPCS Level II and are among the most administratively complex temporary codes in the set. They include codes for physician quality reporting, functional limitation reporting in therapy, telehealth-approved services, preventive care screenings, and various other services that lack permanent CPT or HCPCS codes. Browse G-codes by filtering to G in the code browser.

In outpatient therapy (physical, occupational, and speech-language pathology), G-codes have been required at evaluation, every 10 treatment visits, and at discharge to document the functional limitations affecting the patient. These codes are appended with modifiers indicating the severity of limitation (CH through CN), creating a functional status reporting system embedded in the claim. While some therapy G-code requirements have been phased out in favor of other reporting mechanisms, G-codes remain active for many therapy scenarios.

Telehealth G-codes are particularly significant post-pandemic. CMS assigned G-codes to many telehealth modalities and services to enable Medicare billing for remote visits that did not previously have a billing mechanism. These codes interrelate with place of service codes and telehealth modifiers (95, GT) and must be used correctly to ensure payment.

Because G-codes are temporary, they can be deleted, modified, or replaced without the same notice period as permanent codes. Billers relying on G-codes should monitor the quarterly HCPCS updates closely and maintain a list of active G-codes relevant to their practice. Changes in reporting requirements often accompany code changes.