CO-27CO group · Eligibility

CO-27 denial code: expenses incurred after coverage terminated

CO-27 is an eligibility denial, not a clinical one — so the win, when there is one, is proving the coverage was actually in force on the date of service.

CO-27 means the payer believes coverage had ended before the date of service. Most of the time it is an eligibility or coordination-of-benefits problem to correct rather than appeal. It becomes a true appeal when coverage was in fact active — a retroactive reinstatement, a grace period, or a payer record that is simply wrong.

What CO-27 means

Payers match each claim's date of service against the member's coverage span. A service dated after the termination date denies as CO-27. The question is whether that termination date is accurate for the date you billed.

Why CO-27 fires

  • Coverage genuinely ended before the date of service.
  • Eligibility was verified for an earlier date but lapsed by the time of service.
  • The patient moved to a new plan and the claim went to the prior payer.
  • A retroactive reinstatement or premium grace period was not yet reflected in the payer's system.

Is CO-27 worth appealing?

Rarely an appeal — usually a fix

Usually an eligibility correction, not an appeal: confirm the active plan and rebill the correct payer. Appeal only when you can document that coverage was active on the date of service — a reinstatement letter, a grace-period notice, or an eligibility record contradicting the termination date.

How to resolve or appeal CO-27

  1. 1

    Re-verify eligibility for the exact date

    Confirm which plan was active on the date of service. If a different payer was primary, rebill there rather than appealing.

  2. 2

    Document active coverage

    If the patient was reinstated retroactively or was within a grace period, attach the proof and ask the payer to reprocess against the correct span.

  3. 3

    Escalate a payer record error

    When the payer's termination date is simply wrong, appeal with the enrollment record showing coverage on the date of service.

CO-27 — frequently asked

Is CO-27 worth appealing?
Only when coverage was actually active on the date of service. If the policy had genuinely ended, the path is billing the correct payer or the patient — not an appeal.
How is CO-27 different from CO-26?
CO-27 is service after coverage ended; CO-26 is service before coverage began. Both are eligibility-span problems with the same fix logic.

Related guides

CO-22 · Coordination of benefitsCO-109 · EligibilityCO-29 · Administrative

Sources

Reason-code meanings are paraphrased from the X12 Claim Adjustment Reason Code list for plain-language reference; they are not reproduced verbatim. This is general information, not legal, coding, or medical advice — always confirm against the payer's remittance and policy.

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