CO P29 denial code

Claim adjustment reason code P29. Often reported as CO P29.

Auto liability fee schedule adjustment

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 P29 means

The auto liability carrier reduced the charge to a jurisdictional fee schedule amount.

Auto carriers report it on medical claims under a car insurance policy. P29 is the fee schedule adjustment for liability coverage, similar to P23 for PIP and medical payments.

The payer priced the service at a jurisdictional fee schedule and reported the reduction here. The remittance may identify the schedule used.

Group codes seen with P29

On a remittance, P29 comes after a group code. These are the ones it is most often reported with:

• CO P29 (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 billed amount was above the applicable fee schedule.
• The carrier applied a schedule from a different jurisdiction.
• Fee schedule rules such as multiple procedure reductions lowered the allowance.

What to do next

1. Check the payment against the applicable fee schedule.
2. Ask for reconsideration if the wrong schedule was used.
3. Post the difference as an adjustment if the payment matches.

Related codes

• P28 (reason code) Adjusted under auto liability rules
• P23 (reason code) Auto PIP or MPC fee schedule adjustment
• P12 (reason code) Workers' comp fee schedule adjustment