CO 280 denial code

Claim adjustment reason code 280. Often reported as CO 280 or OA 280.

Medical plan: bill the pharmacy plan

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 280 means

Send this drug or supply to the patient's pharmacy benefit; the medical plan says it is not covered on the medical side.

The medical payer says the drug or supply is covered under the patient's pharmacy benefit, not the medical benefit. The claim was not forwarded; code 292 is used when it was.

This often happens with self administered drugs or supplies the plan routes through its pharmacy benefit manager.

Group codes seen with 280

On a remittance, 280 comes after a group code. These are the ones it is most often reported with:

• CO 280 (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.
• OA 280 (Other Adjustment): Used for adjustments that are neither the provider's contractual write-off nor the patient's share. It often appears with coordination of benefits, for example when another payer already paid.

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

• A self administered drug was billed on a medical claim.
• The plan covers the drug or supply only under the pharmacy benefit.
• The office billed medical without checking the plan's drug benefit rules.

What to do next

1. Check the patient's pharmacy benefit and whether the drug needs prior authorization there.
2. Send the prescription or claim through the pharmacy benefit or a participating pharmacy.
3. Update the drug's billing setup so future claims for this plan route correctly.

Related codes

• 292 (reason code) Medical plan forwarded to pharmacy plan
• 270 (reason code) Medical plan: bill the dental plan