PR 26 denial code

Claim adjustment reason code 26. Often reported as PR 26 or CO 26.

Service before coverage began

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 26 means

The service date falls before the patient's coverage with this payer started, so the plan did not cover it.

On the date of service the patient was not yet covered by this plan, according to the payer's enrollment records. The plan has no obligation for care before its start date.

Often the patient had other coverage at the time, or the start date in the payer's records is wrong. Check before you treat the balance as the patient's.

Group codes seen with 26

On a remittance, 26 comes after a group code. These are the ones it is most often reported with:

• PR 26 (Patient Responsibility): The amount is assigned to the patient. Deductibles, coinsurance and copays are the everyday examples. Whether you can collect it still depends on your contract and the patient's plan.
• CO 26 (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 changed plans and the service was billed to the new plan instead of the old one.
• Eligibility was not checked for the exact date of service.
• The payer's enrollment file has a later start date than the patient expected.

What to do next

1. Run an eligibility check for the date of service and look for other coverage that was active then.
2. Bill the plan that was active on the date of service.
3. Ask the patient to have the plan correct the start date if they believe coverage began earlier.
4. Review the group code before moving any balance to the patient.

Related codes

• 27 (reason code) Service after coverage ended
• 31 (reason code) Payer cannot identify the patient
• 22 (reason code) Another payer may be primary