Who has to pay after a code 233 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 233

Denial code 233: what it means — and how to fight it

Denial code 233 (shown on your EOB as CO-233 or PR-233) means: “Services/charges related to the treatment of a hospital-acquired condition or preventable medical error.” In plain English: The plan will not pay for care needed because of something that went wrong at the hospital, like an infection or a surgical error.

high appealability Usually the provider's problem — not yours

What they're really saying

“Services/charges related to the treatment of a hospital-acquired condition or preventable medical error.”

The plan will not pay for care needed because of something that went wrong at the hospital, like an infection or a surgical error.

Your odds

Strong — this type of denial has real weaknesses.

You generally should not be billed for these at all — the rule exists to keep the cost off the patient.

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 233 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.
Write to the hospital billing office disputing the charge as a hospital-acquired condition. This denial is aimed at the hospital, not you. If any part of it lands on your bill, dispute it in writing and cite this code — payment was denied as a preventable condition, so it is not your responsibility. Request your complete medical record. If patient safety was involved, you can also report it to your state health department or The Joint Commission.
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 233 mean?: The plan will not pay for care needed because of something that went wrong at the hospital, like an infection or a surgical error.
Can I appeal a CO-233 or PR-233 denial?: Yes. Appealing is free and it is your legal right. For this code the odds are high: You generally should not be billed for these at all — the rule exists to keep the cost off the patient. Fewer than 1 in 100 denials are ever appealed — insurers count on silence.
Who has to pay after a code 233 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.