Can I appeal a CO-1 or PR-1 denial?

Yes. Appealing is free and it is your legal right. For this code the odds are low: Only worth fighting if the math is wrong. Fewer than 1 in 100 denials are ever appealed — insurers count on silence.

Who has to pay after a code 1 denial?

Usually your cost to pay. 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 1 · CO-1 / PR-1 · translated

Denial code 1: what it means — and how to fight it

Denial code 1 (shown on your EOB as CO-1 or PR-1) means: “Deductible amount.” In plain English: This isn't a denial — it's your deductible. The plan says you pay this part before coverage kicks in.

low appealability Usually your cost to pay

What they're really saying

“Deductible amount.”

This isn't a denial — it's your deductible. The plan says you pay this part before coverage kicks in.

Your odds

Check the math first — this is usually cost-sharing, not a judgment.

Only worth fighting if the math is wrong.

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 1 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.
Add up what you've already paid toward your deductible this year and check their number. Verify the deductible math: compare year-to-date deductible on this EOB against your other EOBs. Errors in deductible tracking are common early in the year.
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 1 mean?: This isn't a denial — it's your deductible. The plan says you pay this part before coverage kicks in.
Can I appeal a CO-1 or PR-1 denial?: Yes. Appealing is free and it is your legal right. For this code the odds are low: Only worth fighting if the math is wrong. Fewer than 1 in 100 denials are ever appealed — insurers count on silence.
Who has to pay after a code 1 denial?: Usually your cost to pay. 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.