CO 239 denial code

Claim adjustment reason code 239. Often reported as CO 239.

Claim spans covered and uncovered dates

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 239 means

The dates on the claim cross a coverage start or end date, so the payer wants separate claims for each period.

The payer will not process a single claim that mixes covered and uncovered periods. Instead of splitting it itself, it is asking you to rebill.

This usually means two claims: one for the dates the plan covered, and another to whichever payer or party covered the rest.

Group codes seen with 239

On a remittance, 239 comes after a group code. These are the ones it is most often reported with:

• CO 239 (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

• A long service span crossed the date coverage started or ended.
• A recurring monthly bill included days before enrollment.
• The patient changed plans partway through the billed period.

What to do next

1. Confirm the coverage dates with the payer.
2. Split the claim into separate claims along the coverage dates.
3. Send the covered portion back to this payer and bill the other portion to the correct party.

Related codes

• 238 (reason code) Ineligible period reduction (patient)
• 200 (reason code) Service during a gap in coverage
• 27 (reason code) Service after coverage ended