CO P15 denial code

Claim adjustment reason code P15. Often reported as CO P15.

Outside workers' comp treatment guidelines

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 P15 means

The workers' compensation payer reduced or denied care because it does not fit the jurisdiction's medical treatment guidelines.

It appears on workers' compensation claims only. Many jurisdictions adopt treatment guidelines that set what care is expected for an injury, how much, and for how long. P15 means the care billed fell outside those guidelines.

Treatment beyond the guidelines can often still be approved through a variance or prior request process, depending on the state.

Group codes seen with P15

On a remittance, P15 comes after a group code. These are the ones it is most often reported with:

• CO P15 (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 number of visits or sessions went beyond what the guidelines allow.
• The treatment is not recommended in the guidelines for the diagnosis.
• No request was made for care outside the guidelines.

What to do next

1. Check the guideline for the diagnosis and treatment involved.
2. Submit a request for authorization or a variance with clinical support if more care is needed.
3. Appeal through the state's process if the care meets the guideline as written.

Related codes

• P12 (reason code) Workers' comp fee schedule adjustment
• P13 (reason code) Reduced under workers' comp rules
• 50 (reason code) Not medically necessary per the payer