GW Modifier in Medical Billing: When to Use It and Avoid Claim Denials

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Quick answer: The GW modifier tells Medicare that a service is not related to the patient's hospice terminal illness or related conditions. It belongs on a claim only when the patient has elected hospice and the documentation supports that the service is unrelated. It does not guarantee payment.

Picture a Medicare patient who has elected hospice for advanced heart failure. Weeks later that patient needs treatment for an unrelated skin lesion. The claim goes out, and it comes back denied because Medicare sees an active hospice election. Choosing the right modifier, and proving the service is unrelated, decides whether that claim is paid. This guide explains the GW modifier in medical billing, how it differs from GV, and how to avoid the denials that come with mistakes.

Last reviewed: October 16, 2026. Rules vary by claim type and Medicare Administrative Contractor (MAC), so confirm details with your MAC.

What Is the GW Modifier in Medical Billing?

Definition: GW means "Service not related to the hospice patient's terminal condition," as MACs such as CGS and Palmetto GBA describe it.

When a Medicare beneficiary elects hospice, Part B generally stops paying for care related to the terminal illness. Under the Medicare Benefit Policy Manual, Chapter 9, Medicare still pays through the fee-for-service system for services not related to the patient's terminal illness. GW is how a claim signals that distinction.

When Should You Use the GW Modifier?

GW may be appropriate when three things are true: the patient is enrolled in a Medicare-certified hospice for the date of service, the service is not related to the terminal illness or related conditions, and the record supports that conclusion. MACs advise that the provider determine the relationship before billing and verify the hospice election with the patient or representative, the hospice, or the MAC portal.

Not enough on their own: a service performed outside a hospice facility, a non-hospice provider rendering it, or separate billing. None of these makes a service unrelated. The relationship to the terminal illness is what matters.

Illustrative example (hypothetical): A patient enrolled in hospice for advanced heart failure is seen by a dermatologist for a skin lesion. The record documents the condition, the treatment, and why it is unrelated to the heart failure. The practice verifies the hospice dates and reviews the claim before submitting it with GW. If the lesion were treated as part of the terminal illness plan of care, GW would not apply. The final decision depends on the documented facts and current rules.

Medicare billing reminder: Append GV or GW only when the patient is enrolled in a Medicare-certified hospice. On institutional claims (UB-04/837I), MACs also direct providers to append condition code 07, defined in the Claims Processing Manual, Chapter 11 as treatment of a nonterminal condition for hospice. DME suppliers send unrelated items to the DME MAC with GW (per CGS DME guidance).

GW Modifier vs. GV Modifier

Modifier	General meaning	Typical billing context	What it communicates	Verify
GW	Service not related to the hospice patient's terminal condition	Any provider billing Medicare for a documented unrelated service	The service is unrelated	Documentation of the unrelated condition; claim type
GV	Attending physician not employed or paid under arrangement by the patient's hospice provider	Designated attending (MD/DO, NP or PA) billing Part B for attending services	Attending services by a non-hospice-employed attending	Attending designation; no hospice employment or arrangement

They convey different information and are not interchangeable. GV identifies who is billing as the attending. GW identifies services as unrelated to the terminal illness. The Benefit Policy Manual says the attending can be a doctor of medicine or osteopathy, a nurse practitioner, or a physician assistant. Per CMS Transmittal 11200, GV also matters for hospice overlap edits on certain rural health clinic and FQHC claims.

How to Bill the GW Modifier Correctly

Step 1	Confirm the hospice election and relevant dates with the patient, the hospice, or your MAC portal.
Step 2	Review the clinical documentation to establish whether the service is related or unrelated to the terminal illness.
Step 3	Confirm the billing provider, claim type (professional, institutional, or DME), and your MAC's instructions.
Step 4	Verify the procedure code, diagnosis information, modifier placement, and condition code where required.
Step 5	Review the claim before submission and retain the supporting documentation.

GW alone does not establish coverage or guarantee payment. Medicare contractors may conduct prepayment or postpayment review to validate modifier use.

Common GW Modifier Billing Mistakes That Can Lead to Denials

Common mistake	Why it creates a problem	How to prevent it
Using GW without enough documentation	Reviewers cannot confirm the service is unrelated	Document why it is unrelated to the terminal illness
Applying GW to related services	Related services are the hospice's responsibility	Check the plan of care and the diagnosis
Confusing GW with GV	The modifiers communicate different things	Match the modifier to the billing role and service
Assuming anything outside hospice is unrelated	Setting and provider do not decide relatedness	Decide on clinical facts, not location
Wrong placement or incomplete claim data	Claim may reject or process incorrectly	Follow claim form instructions; check condition code 07 where required
Skipping MAC instructions	Requirements vary by claim type and contractor	Review your MAC's current guidance

Outcomes differ. A mistake may cause a rejection, denial, delay, review, or an overpayment risk depending on the facts.

Seeing hospice-related denials?

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Documentation Checklist Before Submitting a GW Claim

☐	Hospice election dates confirmed
☐	Service provided and medical necessity documented
☐	Record clearly supports why the service is unrelated to the terminal illness
☐	Provider role and claim type verified
☐	Coding, diagnosis, and modifier placement checked
☐	Condition code 07 added where required on institutional claims
☐	Current CMS and MAC instructions reviewed

What to Do if a Medicare Claim With GW Is Denied

•      Read the remittance advice and the specific denial reason. Codes such as CO-B9 ("Patient is enrolled in a Hospice") point to a hospice status issue.

•      Check the submitted claim, including modifier placement and condition code.

•      Compare the claim with the medical record and applicable Medicare rules.

•      Correct and resubmit only when appropriate, or follow the redetermination process if you believe the denial was an error.

•      Document the outcome and look for ways to prevent the same error.

Do not add GW to every denied hospice-related claim. Some services are related, and those are not billed with GW. When it is unclear whether to bill the hospice or Medicare, MAC guidance says to contact the hospice and your MAC first.

Frequently Asked Questions About the GW Modifier

▸  What does the GW modifier mean?

GW indicates a service is not related to the hospice patient's terminal condition. It is used on Medicare claims for patients who have elected hospice.

▸  When is the GW modifier appropriate?

When the patient is enrolled in Medicare hospice and the documentation supports that the service is unrelated to the terminal illness and related conditions. Check your MAC's instructions for your claim type.

▸  What is the difference between GW and GV?

GW marks a service as unrelated to the terminal illness. GV identifies attending physician services by an attending who is not employed or paid under arrangement by the hospice. They are not interchangeable.

▸  Can GW be used for every service during hospice enrollment?

No. Only services documented as unrelated qualify. Services related to the terminal illness are generally the hospice's responsibility.

▸  Does using GW guarantee Medicare payment?

No. Payment depends on eligibility, documentation, coverage, and applicable rules. Claims can be reviewed.

▸  What documentation supports GW?

Hospice election dates, the service and its medical necessity, and a clear record of why it is unrelated to the terminal illness. Your MAC may ask for more.

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Sources and Further Reading

•      CMS: Medicare Benefit Policy Manual, Chapter 9 · Claims Processing Manual, Chapter 11 · Transmittal 11200

•      MAC guidance: CGS Part B: Professional services during a hospice election · Palmetto GBA: same topic · CGS DME consolidated billing · CGS hospice education

Disclaimer: This article is for educational and informational purposes only and does not constitute medical, legal, coding, or reimbursement advice. Medicare billing requirements and payer policies may change. Providers should verify current CMS guidance, applicable Medicare Administrative Contractor instructions, and individual payer requirements before submitting claims. Coverage and payment depend on the specific service, documentation, eligibility, and applicable rules.