What is the denial code for provider not credentialed?

Usually CO-185, which means the rendering provider is not eligible with the payer to perform the service, or CO-170 when the payer does not pay that provider type for it. CO-147 is a related contract-side code: the payer has no current rate loaded for the provider. Each one needs the enrollment or contract fixed, not the claim.

Can I bill the patient if the provider was not credentialed?

Generally no. These denials carry a contractual group code because enrollment and credentialing are the provider's responsibility. Fix the enrollment, ask whether the payer will make it retroactive to the date of service, and resubmit.

Provider eligibility and credentialing denial codes

These denials are about who provided or ordered the service, not the service itself. CO-8 means the provider's enrolled specialty does not match the procedure, and CO-170 that the payer does not pay this provider type for the service. CO-185 means the rendering provider is not eligible with the payer to perform the service, and CO-183 that the referring provider is not eligible to refer it. CO-147 points the same direction from the contract side: the payer has no current rate loaded for this provider, often after a renewal or a new provider joining the group.

Also described as: provider not credentialed; rendering provider not enrolled; referring provider not enrolled; provider type not eligible; contract not loaded.

The 5 codes and what separates them

CO-8 - The procedure does not match the provider's type or specialty
The billing or rendering provider's enrolled specialty is not one the payer recognises for this procedure.
Who pays: Provider
CO-170 - This provider type may not be paid for this service
The payer's policy does not pay this service when it is performed or billed by this type of provider.
Who pays: Provider
CO-185 - The rendering provider is not eligible to perform this service
The rendering provider is not enrolled or eligible with the payer to perform and be paid for the service.
Who pays: Provider
CO-183 - The referring provider is not eligible to refer this service
The provider named as the referral source is not enrolled or eligible with the payer to refer the service.
Who pays: Provider
CO-147 - The contracted rate has expired or is not on file
No current contracted rate is loaded for the provider or service, so the payer cannot price the claim.
Who pays: Provider

How to tell which one you have

Check the provider identifiers on the claim before calling anyone: the rendering, referring, and billing NPIs in the right loops, and the taxonomy code that tells the payer the specialty. Many of these resolve once the claim names the provider the payer actually has on file. If the identifiers are right, the problem is enrollment. CO-185 and CO-183 need the provider enrolled or the enrollment effective date corrected - for Medicare, ordering and referring providers must be enrolled in PECOS. CO-147 needs the contract or provider linkage loaded on the payer's side. Escalate those through provider relations, because every claim from that provider will deny the same way until it is fixed.

Frequently asked questions

What is the denial code for provider not credentialed?: Usually CO-185, which means the rendering provider is not eligible with the payer to perform the service, or CO-170 when the payer does not pay that provider type for it. CO-147 is a related contract-side code: the payer has no current rate loaded for the provider. Each one needs the enrollment or contract fixed, not the claim.
Can I bill the patient if the provider was not credentialed?: Generally no. These denials carry a contractual group code because enrollment and credentialing are the provider's responsibility. Fix the enrollment, ask whether the payer will make it retroactive to the date of service, and resubmit.

Other denial reasons

Out of network No prior authorization Not medically necessary Service not covered Bundled or not paid separately Coding mismatch or invalid code Patient not eligible or coverage ended Another payer is responsible Missing information, duplicate, or late filing Benefit or unit limit reached Deductible, coinsurance, or copay Paid less than billed

Every denial code in one table

Last reviewed October 3, 2026.

These are original plain-English summaries written for reference, not the official X12 code descriptions. Payer handling of any code varies by contract - always verify against the remittance advice and your payer agreement before adjusting a claim.