EOB denial code · CO group
CO-45: Charge Exceeds Fee Schedule — Meaning & Who Pays
CO-45 means the provider's charge was higher than the insurer's negotiated rate (fee schedule or maximum allowable). The difference is a contractual write-off: if your provider is in-network, you do NOT owe this amount. CO-45 is the most common adjustment on EOBs and is almost always the "gap" between billed and allowed that the provider agrees to absorb.
What “CO-45” means on your EOB
Charges exceed our fee schedule or maximum allowable or contracted/legislated fee arrangement.
Who pays? CO — Contractual Obligation
CO (contractual) — this is the provider's write-off. The in-network provider accepts the insurer's allowed amount and may not bill you for the difference.
What to do next: CO-45 isn't appealable because it's a math adjustment — the allowed amount is set by your contract. The right move is to verify the provider's in-network status and your allowed amount. If the provider sends you a bill for the CO-45 difference, cite it on the phone and ask them to write it off; balance billing an in-network patient for the rate gap violates most provider contracts.
Why this denial happens
- Provider billed more than the plan's allowed amount for the code.
- Provider is out-of-network and billed at a higher rate than the plan pays for OON care.
- The carrier applied a fee schedule (e.g., Medicare-based) to a provider with no contracted rate.
- Multiple line items on one claim where only part exceeded the schedule.
What to do now
- Locate the line on your EOB: 'billed' vs 'allowed' — the difference is the CO-45 amount.
- Confirm your provider is in-network (check your plan portal or call).
- If in-network and the provider bills you for the CO-45 amount, call their billing office and ask them to adjust it off — it's a contracted write-off.
- If out-of-network, verify the OON allowed amount against your plan's OON policy; big gaps may be worth an appeal under your state's balance-billing protections.
📄 Denied a claim? Generate a free appeal letter
Turn your denial into a ready-to-send reconsideration letter — no registration, no account.
Generate an appeal letter →Do I owe the CO-45 amount on my EOB?
If the provider is in-network, no — CO-45 is a contractual write-off. The provider agrees to accept the insurer's allowed amount. Only an out-of-network provider could bill you the difference, subject to your plan and state rules.
What's the difference between billed and allowed?
Billed is what the provider charges. Allowed is the maximum your plan will consider. The gap is usually written off (CO-45) for in-network providers; you pay only your deductible/coinsurance/copay on the allowed amount.
Can CO-45 be appealed?
No — it's a rate adjustment, not a coverage decision. If you think the allowed amount is wrong for your plan, that's a different dispute: ask your insurer to reprice the claim, but don't frame it as an appeal of CO-45.