Who has to pay after a code 256 denial?

Usually the provider's problem — not yours. The letters in front of the number matter: CO (contractual obligation) usually means an in-network provider must absorb it, while PR (patient responsibility) means the plan says you owe it.

How long do I have to appeal?

It depends on your coverage: 180 days for most employer and marketplace plans, 120 days for Original Medicare, about 90 days for Medicaid (varies by state), and only 65 days for Medicare Advantage. Set your deadline clock before you do anything else.

All denial codes · code 256

Denial code 256: what it means — and how to fight it

Denial code 256 (shown on your EOB as CO-256 or PR-256) means: “Service not payable per managed care contract.” In plain English: Your plan's contract with this provider says the service is not payable — and usually says the provider cannot bill you for it either.

medium appealability Usually the provider's problem — not yours

What they're really saying

“Service not payable per managed care contract.”

Your plan's contract with this provider says the service is not payable — and usually says the provider cannot bill you for it either.

Your odds

Worth fighting — many of these get fixed.

You often owe nothing; the real fight is between the plan and the provider.

Fewer than 1 in 100 denied claims are ever appealed. When people do appeal, roughly 4 in 10 win the first round — and independent external review overturns 40–50% of what reaches it.

How to appeal a code 256 denial

Decode. You just did — this page is step one.
Set your clock. 180 days for most employer and marketplace plans, 120 for Original Medicare, ~90 for Medicaid, only 65 for Medicare Advantage.
Urgent? If this is care you still need, call and request an expedited appeal — they must decide within 72 hours.
Ask your plan in writing whether the provider is allowed to bill you. Ask the plan in writing whether you are held harmless under the provider's contract — under most managed-care and capitated arrangements you are. If the answer is yes, forward it to the billing office and request a zero balance. Separately, if the service was medically necessary and nobody told you it was not covered, ask for the denial to be reviewed on medical necessity so a legitimate service does not just get written off.
Send it certified. Letter plus evidence, keep copies of everything.
Escalate. Denied again? Independent external review — a doctor who doesn't work for your insurer decides.

Do it in minutes, free

The AppealClock tool translates your denial, drafts your appeal letter, computes your exact deadline — and watches the clock so you don't have to. No account. Your medical details never leave your device.

Start your appeal & set your clock →

Common questions

What does denial code 256 mean?: Your plan's contract with this provider says the service is not payable — and usually says the provider cannot bill you for it either.
Can I appeal a CO-256 or PR-256 denial?: Yes. Appealing is free and it is your legal right. For this code the odds are medium: You often owe nothing; the real fight is between the plan and the provider. Fewer than 1 in 100 denials are ever appealed — insurers count on silence.
Who has to pay after a code 256 denial?: Usually the provider's problem — not yours. The letters in front of the number matter: CO (contractual obligation) usually means an in-network provider must absorb it, while PR (patient responsibility) means the plan says you owe it.
How long do I have to appeal?: It depends on your coverage: 180 days for most employer and marketplace plans, 120 days for Original Medicare, about 90 days for Medicaid (varies by state), and only 65 days for Medicare Advantage. Set your deadline clock before you do anything else.