Medicare Denied Over Provider or Network Issues on Medicare Denial Guide — Barley

Medicare Denied Claim: Need Primary Care Referral

Thu, 26 Mar 2026 00:00:00 +0000

What This Means

Your Medicare Advantage plan denied this claim because you saw a specialist without first getting a referral from your primary care provider (PCP). Many Medicare Advantage HMO plans require your PCP to authorize specialist visits before you go. Without that referral, the plan may refuse to pay. On your notice this usually appears as CARC code CO-242, “services not provided by network/primary care providers.”

This requirement does not apply to Original Medicare. If you have Original Medicare (not a Medicare Advantage plan), you do not need referrals to see specialists.

Medicare Denied Claim: Out-of-Network Provider

Thu, 26 Mar 2026 00:00:00 +0000

What This Means

Your Medicare Advantage plan denied your claim because the doctor, hospital, or other provider who treated you is not part of your plan’s approved network. The plan is saying it will not pay for care from this provider.

This type of denial is almost always a Medicare Advantage issue. Original Medicare does not use provider networks — if you have Original Medicare (Parts A and B without a Medicare Advantage plan), you can see any provider who accepts Medicare.

Medicare Denied Claim: Provider Not Enrolled

Thu, 26 Mar 2026 00:00:00 +0000

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.”

Medicare Denied Your Claim Over Who Treated You

Thu, 26 Mar 2026 00:00:00 +0000

What This Means

Medicare denied this claim with CARC CO-170, “Payment is denied when performed/billed by this type of provider” — or one of its relatives: CO-171 (the same, “in this type of facility”), CO-172 (“Payment is adjusted when performed/billed by a provider of this specialty”), or CO-8 (“The procedure code is inconsistent with the provider type/specialty (taxonomy)”). The two-letter prefix decides who pays: CO stands for “contractual obligation,” and CMS’s claims manual says CO adjustments are generally “considered a write off for the provider and are not billed to the patient” (Medicare Claims Processing Manual, Chapter 22, §60.1). Call your provider’s billing office, ask them to correct and resubmit the claim, and ask them to put in writing any reason they believe you owe.