Contractual

Denial code CO-45: Charge exceeds fee schedule / maximum allowable

The billed charge was above the contracted allowed amount, and the difference is a contractual write-off — not a balance you may bill the patient.

Reason code

CARC 45

Typical group code

What CO-45 actually means

CO-45 is the single highest-dollar line item in most remittances and is not a denial: it is the contractual adjustment between your charge and the payer’s allowed amount. Under a participating-provider agreement that difference must be written off. What makes CO-45 worth monitoring rather than auto-posting is that it is also where underpayments hide — if the allowed amount is below your contracted rate, the payer has underpaid and the difference is recoverable, but it looks identical to a normal adjustment unless you are comparing every allowed amount against the contract.

Why this denial happens

Normal contractual adjustment on an in-network claim.
The payer priced the line against an outdated or incorrect fee schedule.
A contracted rate increase was never loaded on the payer’s side.
The claim was priced out-of-network although the provider is participating.

How to resolve a CO-45 denial

Compare the allowed amount to your contracted rate for that code before writing anything off.
Where the allowed amount is short of the contract, dispute it as an underpayment and cite the contracted rate.
Where the allowed amount matches the contract, post the write-off — balance billing the patient for this amount violates most participating agreements.

How to prevent it

Load contracted rates into the system and reconcile every allowed amount against them automatically.
Re-check the loaded fee schedule after each contract renewal — unloaded rate increases are a large and silent revenue leak.

Frequently asked

What does denial code CO-45 mean?

The billed charge was above the contracted allowed amount, and the difference is a contractual write-off — not a balance you may bill the patient. The X12 description reads: "Charge exceeds fee schedule, maximum allowable, or contracted/legislated fee arrangement."

How do I fix a CO-45 denial?

Compare the allowed amount to your contracted rate for that code before writing anything off. Where the allowed amount is short of the contract, dispute it as an underpayment and cite the contracted rate. Where the allowed amount matches the contract, post the write-off — balance billing the patient for this amount violates most participating agreements.

Can CO-45 be billed to the patient?

No. This is a contractual adjustment, and participating provider agreements generally prohibit billing the patient for it.

Related denial codes

CO-59 · Processed under multiple or concurrent procedure rules CO-97 · Service bundled into another payment OA-23 · Impact of prior payer adjudication CO-242 · Services not provided by network providers

Related billing terms

EDI 835 CARC (Claim Adjustment Reason Code)First-pass resolution rate Underpayment (payment variance)

See how much CO-45 is costing you

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General revenue-cycle guidance, not legal, coding, or payer-specific advice. Claim adjustment reason codes are maintained by X12 and are revised periodically; payer policy and your provider agreement govern in any specific case. Always read the remark codes transmitted with the denial — they frequently carry the detail this code does not.