CO 171 denial code

Claim adjustment reason code 171. Often reported as CO 171.

Denied for provider type in this facility

Unofficial reference. This is our own plain-English explanation, not the official code text. Payer rules differ. Verify with the payer and the official X12 code list. AlphaPrefix is not affiliated with X12, CMS or any payer. Data last updated Nov 11, 2026.

What 171 means

Payment was refused because the payer does not pay this provider type for this service in this kind of facility.

This is a combination rule: the provider type is allowed, and the facility type is allowed, but not together for this service. The payer will not pay when the two meet.

Check the place of service, facility type and provider type on the claim. An incorrect place of service is a frequent cause.

Group codes seen with 171

On a remittance, 171 comes after a group code. These are the ones it is most often reported with:

• CO 171 (Contractual Obligation): The provider's side of the ledger. The reduction comes from the payer contract or a rule the provider has to follow, and the patient normally cannot be billed for it.

The payer chooses the group code for each adjustment, so the same reason code can appear with another group code on your remittance. Read the two together. More about group codes.

Common causes

• The payer does not pay this provider type for services in this facility type.
• The place of service on the claim did not match where the service was actually given.
• The facility or provider type is recorded wrong in the payer's file.

What to do next

1. Check the place of service and facility details on the claim.
2. Confirm the payer's rules for this provider type in this setting.
3. Correct and resubmit if the claim data was wrong, or appeal with the policy if it was right.

Related codes

• 170 (reason code) Denied for this type of provider
• 58 (reason code) Wrong or invalid place of service