Modifier GF: Non-Physician Services in a Critical Access Hospital
Modifier GF identifies non-physician practitioner services in a critical access hospital, used on Method II CAH billing. Full usage rules.
When to Append Modifier GF
Append GF to identify that a service delivered in a critical access hospital was performed by a non-physician practitioner rather than a physician.
- Applying GF outside the critical access hospital setting, or omitting it on Method II claims where a non-physician practitioner delivered the service.
Source: HCPCS Level II official descriptor
Modifier GF in Detail
Modifier GF identifies a service performed in a critical access hospital by a non-physician practitioner rather than by a physician. It applies to nurse practitioners, clinical nurse specialists, physician assistants, certified registered nurses and certified registered nurse anesthetists working in that setting.
Its use is tied to Method II critical access hospital billing, where the facility bills the professional component on behalf of the practitioner. Getting it wrong affects how the claim is priced, which makes it a specific concern in hospital billing and in rural facilities alongside rural health clinic billing. Critical access claims run through hospital billing services and follow Medicare billing rules, with the clinic side covered in rural health clinic billing. Modifier use is a compliance matter as much as a billing one, covered in medical billing compliance.
Using Modifier GF Correctly
When to Apply
Apply this modifier only when the clinical circumstances described in the modifier definition are present and documented in the medical record.
Procedure Code Compatibility
Confirm this modifier is applicable to the procedure codes being billed. Not all modifiers are valid with all CPT codes.
Documentation Support
Ensure the medical record supports the modifier's use. Auditors will review documentation to confirm the modifier is appropriate.
Payer Acceptance
Verify that the payer accepts this modifier and understand how it affects reimbursement before submitting the claim.
Modifier GF Reference
| Field | Details |
|---|---|
| Modifier | GF |
| Official Description | Non-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. |
| When to Use | Append GF to identify that a service delivered in a critical access hospital was performed by a non-physician practitioner rather than a physician. |
| Billing Method | Used in Method II critical access hospital billing, where the facility bills the professional component on behalf of the practitioner who delivered the service. |
| Why It Matters | The modifier tells the payer which type of practitioner delivered the service, which affects how the professional component is priced. Omitting it on a Method II claim misrepresents who performed the work. |
| Credentialing Dependency | The practitioner must be properly enrolled and, where applicable, reassigned to the facility before services can be billed. A credentialing gap denies the claim regardless of the modifier. |
| Common Error | Applying GF outside the critical access hospital setting, or omitting it on Method II claims where a non-physician practitioner delivered the service. |
Source: HCPCS Level II official descriptor
Modifier GF, Frequently Asked Questions
Non-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.
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