Denial code CO-45: charge above the allowed amount
Also printed as PR-45, OA-45, PI-45 or 45
CO-45 means: The charge is more than the plan's allowed amount. With group code CO, an in-network provider has to write off the difference. This is an adjustment, not a denial. Can they bill you for it? Usually no. CO means the provider has to write this off under its contract with the plan.
Who usually fixes it
Nobody: it is an adjustment, not a denial.
What CO-45 means
The charge is more than the plan's allowed amount. With group code CO, an in-network provider has to write off the difference.
How CO, PR, OA and PI change it
The letters in front of the number are the group code. They say who the plan thinks owes the amount, so they change whether the provider can bill you, not what the code means.
| Code | Can the provider bill you? |
|---|---|
| CO-45 Contractual obligation | Usually no. CO means the provider has to write this off under its contract with the plan. |
| PR-45 Patient responsibility | Yes. PR means the plan says this amount is yours, unless the decision changes. |
| OA-45 Other adjustment | It depends. Ask the provider's billing office. |
| PI-45 Payer-initiated reduction | Usually no. PI means the plan reduced it under its own policy. |
Appeal rights by plan type
If you think the amount is wrong, ask the plan to explain it. Your appeal rights and deadlines depend on your plan:
- Most private plans
- Marketplace and individual plans
- Job-based plans
- Fully insured job-based plans
- Self-funded job-based plans (ERISA)
- Original Medicare
- Medicare Advantage
- Medicare Part D drug plans
- Medicaid and CHIP
Quick answers
- What does denial code CO-45 mean?
- The charge is more than the plan's allowed amount. With group code CO, an in-network provider has to write off the difference. This is an adjustment, not a denial.
- Can the provider bill me for CO-45?
- Usually no. CO means the provider has to write this off under its contract with the plan.
- What is the difference between CO-45 and PR-45?
- The reason is the same: The charge is more than the plan's allowed amount. With group code CO, an in-network provider has to write off the difference. The group code changes who pays. CO-45: Usually no. CO means the provider has to write this off under its contract with the plan. PR-45: Yes. PR means the plan says this amount is yours, unless the decision changes.
- Who fixes CO-45?
- Nobody: it is an adjustment, not a denial. This is an adjustment, not a denial.
Codes are from the national X12 lists, in plain words. Your notice and your plan are the final word on why a claim was denied. General information, not legal advice.
Sources
- https://x12.org/codes/claim-adjustment-reason-codes
- https://x12.org/codes/remittance-advice-remark-codes
Ask Appeal My Claim yourself
Type any code from your Explanation of Benefits, like CO-50, PR 204 or N130, and get it in plain words, with a letter when an appeal fits. Open Appeal My Claim, free, no sign-up.
In Claude or any app that takes MCP connectors, add https://goodturn-mcp.pages.dev/appealmyclaim/mcp and ask: “My EOB says CO-45, what does that mean?”