CO P17 denial code

Claim adjustment reason code P17. Often reported as CO P17.

Referral not authorized by attending

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 P17 means

On a property and casualty claim, the attending physician did not authorize the referral as the regulations require.

Property and casualty payers, including workers' compensation and auto carriers, are the only ones that use it. In many workers' compensation and auto systems, care by another provider must be referred by the treating or attending physician. P17 means that referral was not on record.

The usual fix is to get the referral documented and request reprocessing, if the rules allow it after the fact.

Group codes seen with P17

On a remittance, P17 comes after a group code. These are the ones it is most often reported with:

• CO P17 (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 patient self-referred to a specialist or therapist.
• The referral was not sent to the carrier before treatment.
• The referring provider was not the attending physician of record.

What to do next

1. Get a copy of the referral from the attending physician, if one exists.
2. Send the referral to the carrier and ask for reprocessing.
3. Set up a process to confirm referrals before scheduling property and casualty patients.

Related codes

• P16 (reason code) Provider not authorized for workers' comp
• P15 (reason code) Outside workers' comp treatment guidelines