Notes on payer behavior
CO-27 denial code: coverage terminated before the date of service
Denial code CO-27 is the payer saying: "Expenses incurred after coverage terminated." In short: Usually the patient's plan ended before the date of service. Rarely recoverable, so check the end date and whether a new plan picked up the visit before writing it off.
What the payer is asserting
The patient's coverage under this plan ended on a date before the service. The claim is denied in full and the amount is coded CO, which on its face says the practice eats it. That's the part to question. Termination denials are among the few where the group code should often be PR: if the patient had no coverage, the patient owes the bill, and a CO-27 on an in-network claim with a genuinely terminated policy is usually a payer coding choice, not a contractual truth.
Three checks before anything else
- The termination date against the date of service. Pull the eligibility response you ran at the visit. If it showed active coverage on the date of service, you have a retroactive termination, and that changes the conversation with both the payer and the patient.
- Whether the patient moved to another plan. Employer changes, a spouse's plan, Medicare turning on, marketplace re-enrollment. The claim may be recoverable in full at the new payer, inside its filing window, which is why CO-27s need to be worked in the month they arrive, not the quarter.
- Whether the termination is real. Premium lapses get cured, COBRA elections arrive late, and employer files get corrected. A payer that reinstates coverage retroactively will reprocess a denied claim if you ask. Silence won't trigger it.
Is it recoverable?
From the payer, only when the termination is wrong, gets reversed, or came too late. From another payer, yes, when the patient had other coverage. From the patient, yes, when the coverage truly ended, once the group code is corrected to PR or the payer confirms the patient's liability in writing. The worst outcome is the common one: the CO-27 is posted as a contractual write-off and the practice never bills anyone.
Florida's one-year rule on retroactive denials
On fully insured Florida business, an insurer that has already paid a claim cannot come back later and take it back on eligibility grounds without limit. Section 627.6131(11) says a health insurer "may not retroactively deny a claim because of insured ineligibility more than 1 year after the date of payment of the claim." That protects paid claims, not first-time denials. But it is the answer when a CO-27 arrives as an overpayment demand on a claim paid eighteen months ago. The statutory text, and the offset bar that goes with it. The statute contains no rule keyed to eligibility verified at the time of service, so don't argue one; argue the date.
The patient conversation
Once you've confirmed the coverage ended, the patient gets a statement that says so plainly, with the payer's termination date, and an offer to bill any new plan they name. Practices lose more on CO-27 by never sending that statement than by any payer's behavior. The claim is the patient's to pay or to help you redirect.
The other end of the plan has its own code. A service before the patient's coverage started comes back as CO-26, expenses incurred prior to coverage, and the checks are the same: the eligibility response, the other plan, and the group code.
Source: the code descriptions on this page are quoted from the X12 Claim Adjustment Reason Code list, the standard code set every payer remittance uses.
Questions people ask about CO-27
What does denial code CO-27 mean?
The payer says the patient's coverage under the plan ended before the date of service, so the plan owes nothing on the claim.
What's the difference between CO-27 and PR-27?
Same reason, different group code. PR-27 says the patient owes the charge because their coverage had ended, which is the normal way a payer reports it. CO-27 puts the write-off on the practice instead, which rarely fits a terminated plan, so it's worth asking the payer to correct it to PR or explain why the practice is liable.
Can I bill the patient for a CO-27 denial?
If the coverage genuinely ended, yes, the patient is responsible, and the group code should be PR rather than CO. Ask the payer to correct the group code or confirm patient liability in writing, and check for any new coverage first.
What if eligibility showed active coverage on the date of service?
That's a retroactive termination. Send the eligibility response to the payer and ask for reconsideration. On fully insured Florida business, an insurer cannot retroactively deny an already-paid claim for ineligibility more than one year after the payment date.