CO-27 Denial Code: Expenses Incurred After Coverage Terminated

What Does CO-27 Mean?

CO-27 means the payer's records show the patient's coverage ended before the date of service. The plan isn't disputing the care — it's saying the patient simply wasn't insured with them anymore when it happened.

Code group: CO (Contractual Obligation) · Appealable: Yes when termination data is wrong or reinstated; otherwise it's a redirect (new payer) or patient-responsibility conversation.

Why CO-27 Happens

The patient lost or changed jobs, and employer coverage terminated — often with the patient unaware of the exact end date or assuming COBRA kicked in automatically.
Non-payment of premiums terminated an individual/marketplace plan — sometimes retroactively after a grace period expired, clawing back dates that looked covered when you verified.
The patient switched plans and presented the old card; the new coverage exists, just not with the payer you billed.
Medicaid eligibility lapsed at a redetermination date the patient missed.
The termination date in the payer's system is simply wrong — retro-terminations get reversed, and employer files get corrected.

How to Fix a CO-27 Denial — Step by Step

Ask the patient about their current coverage — the most common outcome is that new coverage exists and the claim just needs redirecting to it.

Verify the termination date with the payer. If the patient believes they were covered (COBRA elected, premiums paid, employer error), have them contact the plan or their HR department; reinstatements happen regularly and reprocess cleanly.

For marketplace grace-period retro-terminations, determine which dates fall inside the paid period — some services may still be payable.

If new coverage is found, bill it with proof of the original denial to protect timely filing.

If no coverage existed on the DOS, the balance moves to the patient as self-pay — communicate promptly and offer a plan; these balances collect far better in month one.

CO-27 Appeal Letter Template

Adapt this wording to your claim — replace the bracketed fields and attach the documentation it references:

Appeal only when coverage actually existed: 'Claim [number] was denied CO-27 indicating coverage terminated [date]. Per the attached [COBRA election and premium proof / employer confirmation / reinstatement letter], the member's coverage was active on [DOS]. We request enrollment correction and claim reprocessing.' Otherwise, redirect to the real payer or transition the balance to the patient.

How to Prevent CO-27

Verify eligibility at every visit — termination denials are the textbook argument for it.
Re-verify before high-cost scheduled services even if checked at booking.
Flag marketplace patients in premium grace periods when eligibility responses disclose it — their claims can pend or retro-deny.

Related Denial Codes

CO-22 — COB / other payer CO-109 — Wrong payer

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Reviewed by the LegitMedBilling denial management team. This guide is general billing information, not legal or payer-specific advice — always verify against your payer contract and current policy.

Frequently Asked Questions

Can we bill the patient after a CO-27 denial?

Yes — if coverage truly didn't exist on the date of service, the patient is self-pay for that visit, and you should bill them promptly with a clear explanation. The exceptions: Medicaid patients (state rules restrict billing in many situations) and cases where your own verification error created the mess — handle those with judgment.

The patient says they elected COBRA. Why is the claim still denying?

COBRA elections take time to process, and coverage is retroactive once premiums are paid — but until the plan's system catches up, claims deny CO-27. Hold the claims, confirm the election and payment went through, then resubmit or request reprocessing. Don't write off or patient-bill mid-limbo.

We verified eligibility and it showed active — then the claim denied CO-27. How?

Retro-termination. Marketplace grace periods, employer file corrections, and premium non-payment can terminate coverage backwards, after your check showed active. Keep your eligibility response — it supports both an appeal and, failing that, a clean patient-responsibility transition since you verified in good faith.