Medicare Denied Claim: Provider Not Enrolled

What This Means

Medicare denied this claim because the provider who treated you is not enrolled in the Medicare program. All providers who bill Medicare must complete an enrollment process with CMS (the Centers for Medicare & Medicaid Services). If a provider has not completed this step, Medicare cannot pay the claim. On your notice this usually appears as CARC code CO-B7, “this provider was not certified/eligible to be paid for this procedure/service on this date of service.”

This matters for what you might owe: because the provider – not Medicare – failed to meet the enrollment requirement, you may have grounds to dispute a bill, especially if you were led to believe the provider accepted Medicare. But Medicare treats the service as non-covered, so whether you ultimately owe depends on your situation.

Why This Happens

• The provider never enrolled in Medicare. Some providers, especially newer practices or certain specialist types, may not have completed Medicare enrollment.
• The provider’s enrollment lapsed. Medicare enrollment must be renewed periodically. If a provider missed their revalidation deadline, their enrollment may have been deactivated.
• The provider recently changed practice locations. Providers must update their enrollment when they change locations. If they did not, claims from the new location may be denied.
• An ordering or referring provider isn’t enrolled. Medicare requires that the provider who ordered or referred a service also be enrolled in Medicare. If only the ordering provider is unenrolled, the claim can be denied.

Should You Appeal?

What To Do Next

1. Don’t rush to pay – but don’t ignore the bill. First ask the provider to enroll and resubmit the claim. Find out why you’re being billed and whether you were told the provider accepted Medicare. If you believe the charge is improper, dispute it in writing rather than simply not paying.
2. Contact the provider’s billing office. Let them know the claim was denied due to an enrollment issue. Ask them to enroll in Medicare and resubmit the claim.
3. If the provider bills you, ask them to enroll and resubmit the claim first. If you believe you were misled about their Medicare status, put your dispute in writing and keep a copy.
4. Call 1-800-MEDICARE (1-800-633-4227) to report the situation if the provider insists on billing you. Medicare can help clarify the provider’s obligations.
5. For future visits, verify that your provider is enrolled in Medicare before scheduling. You can check on Medicare.gov or by calling 1-800-MEDICARE.

Sources

• CMS: Medicare Provider Enrollment
• eCFR: 42 CFR 424.521 — Request for payment by providers and suppliers (retrospective billing)
• CMS: Provider Enrollment & Third-Party Liability FAQs (services from non-enrolled providers are non-covered)
• X12: Claim Adjustment Reason Codes — official CARC code definitions
• Medicare.gov: Find Providers & Compare Care

Frequently Asked Questions