Can I appeal a CO-155 or PR-155 denial?

Yes. Appealing is free and it is your legal right. For this code the odds are medium: many denials are reversed when challenged with the right evidence. Fewer than 1 in 100 denials are ever appealed — insurers count on silence.

Who has to pay after a code 155 denial?

Who owes depends on the details. 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.

Denial code 155 · CO-155 / PR-155 · translated

Denial code 155: what it means — and how to fight it

Denial code 155 (shown on your EOB as CO-155 or PR-155) means: “Patient refused the service/procedure.” In plain English: Their records say you refused the care that was then billed. If you didn't refuse, the record is wrong.

medium appealability Who owes depends on the details

What they're really saying

“Patient refused the service/procedure.”

Their records say you refused the care that was then billed. If you didn't refuse, the record is wrong.

Your odds

Worth fighting — many of these get fixed.

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 155 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 to see where and when the refusal was documented. Dispute the record with your own account and any documentation; ask where the refusal is documented and by whom.
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 155 mean?: Their records say you refused the care that was then billed. If you didn't refuse, the record is wrong.
Can I appeal a CO-155 or PR-155 denial?: Yes. Appealing is free and it is your legal right. For this code the odds are medium: many denials are reversed when challenged with the right evidence. Fewer than 1 in 100 denials are ever appealed — insurers count on silence.
Who has to pay after a code 155 denial?: Who owes depends on the details. 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.