Claim adjustment reason code
CO-45: Charge exceeds the fee schedule
CO-45 means: Charge exceeds fee schedule/maximum allowable or contracted/legislated fee arrangement. A contractual write-off rather than a denial. It only becomes a problem when the allowed amount is wrong.
Read the group code before you act on this
45 is the claim adjustment reason code. The CO in front of it is the group code — a separate field the payer sets on the remittance. The same reason code arrives under different group codes depending on the payer and the situation, and the group code, not the reason code, decides who owes the money.
- CO — contractual obligation. You write it off. You may not bill the patient.
- PR — patient responsibility. Billable to the patient.
- OA — other adjustment, and PI — payer initiated reduction. Neither is patient responsibility.
What causes it
- Normal contractual adjustment, correct and expected
- The payer loaded the wrong fee schedule for your contract
- The claim was priced as out of network when you are in network
- A contract escalation was agreed and never applied on the payer side
How to work it
- Compare the allowed amount against your contracted rate for that CPT. If they agree, post the adjustment and move on
- If the allowed amount is short, this is a payer configuration error and it is affecting every claim for that code, not just this one
- Escalate underpayments as a batch with a spreadsheet of examples rather than one call per claim
- Recalculate after every contract renewal, because this is when loaded rates most often go stale
How to stop it recurring
Most practices post CO-45 automatically and never check it. Systematic underpayment hides here precisely because the code looks routine.
Who does this work
A ar calling & denial management seat at $1,700 per seat per month works this queue full time, during your business hours, inside your own system. Every call is logged with the payer reference number and the outcome, and every Friday you get it in writing.
Codes worked the same way
CO-45 is checked against the contract before any work is done. So are these, which is why a queue sorted by recovery route moves faster than one sorted by code number — the same person, in the same system, with the same evidence to hand, clears all of them in one pass.
- CO-97 — Payment included in another service
- CO-18 — Exact duplicate claim or service
- CO-288 — Referral absent
- PR-204 — Not covered by this plan
- OA-23 — Prior payer already adjudicated
- CO-286 — Appeal filed too late
Specialties that name this among their costliest
These are specialties whose own worst denials include one of this kind. The line under each is the denial they name, quoted from their page so you can see what the link is based on.
- AnesthesiaPost-op pain blocks bundled into the anesthesia claim
- OphthalmologyRetinal imaging and fundus photography done at the same visit, with one line denied as bundled because the record never gives a separate reason for each test.
- OtolaryngologyThe operative note does not state which sinuses were entered on which side, so the sinus surgery lines are bundled together or only one side is allowed.
- Urgent CareA global urgent care case rate billed alongside a separate evaluation and management line where the contract pays one or the other, and the second line drops off
- Primary CareA preventive visit and a same-day problem visit written up in one undivided note, so the problem visit bundles into the wellness visit and is not paid separately.
- OncologyPayer required the drug through its contracted specialty pharmacy, the practice infused from its own stock, and the buy-and-bill claim was denied in full.
What leaving it costs
Working a denied claim costs $57.23 per denied claim in administrative time. Source. At 100 denials a month — an illustration, not a measurement of your practice — that is $5,723 a month, or $68,676 a year, in labour alone.
The figure that makes it worth spending: about 90% of initially denied claims are eventually paid. Source. The reason a denial sits is almost never that nobody knows how to work it — it is that nobody has the hours.
Questions
What does denial code CO-45 mean?
Charge exceeds fee schedule/maximum allowable or contracted/legislated fee arrangement. In plain terms: A contractual write-off rather than a denial. It only becomes a problem when the allowed amount is wrong.
What causes CO-45?
Normal contractual adjustment, correct and expected. The payer loaded the wrong fee schedule for your contract. The claim was priced as out of network when you are in network. A contract escalation was agreed and never applied on the payer side.
How do you fix a CO-45 denial?
Compare the allowed amount against your contracted rate for that CPT. If they agree, post the adjustment and move on. If the allowed amount is short, this is a payer configuration error and it is affecting every claim for that code, not just this one. Escalate underpayments as a batch with a spreadsheet of examples rather than one call per claim. Recalculate after every contract renewal, because this is when loaded rates most often go stale.
Can CO-45 be prevented?
Most practices post CO-45 automatically and never check it. Systematic underpayment hides here precisely because the code looks routine.
Is CO-45 the same as PR-45?
Same reason, different group code. The number 45 is the reason: A contractual write-off rather than a denial. It only becomes a problem when the allowed amount is wrong. The prefix says who carries the amount. CO means contractual obligation — the payer says the amount is not billable to anybody, and it is written off unless the denial itself is overturned. PR-45 is the same reason assigned to patient responsibility — the payer says the amount is owed by the patient, and it is billed to them. Read the prefix before the number: it decides whether you appeal, write off, or bill the patient.
What about the codes next to CO-45?
CO-44 and CO-46 are separate codes and this site does not yet cover them. The authoritative list is the X12 Claim Adjustment Reason Codes at x12.org/codes/claim-adjustment-reason-codes; a code is only described here once its official text, causes and fix have been written and checked.
Code descriptions are the standard X12 claim adjustment reason and remittance advice remark code text. Payer policies differ, and the payer’s own coverage policy governs any individual claim. This page is working guidance, not legal or clinical advice.
Last updated 2026-09-12. This is operational guidance drawn from payer remittance practice, not legal, coding or reimbursement advice. Payer-specific rules vary and change; confirm against the payer’s own policy before acting on a specific claim.
Other denial codes
- OA-23 — Prior payer’s adjudication
- N381 — Adjusted per the contract — read the contract
- CO-10 — Diagnosis inconsistent with patient gender
- CO-15 — Authorization number missing or invalid
- CO-B7 — Provider not certified or eligible on this date
- CO-29 — Time limit for filing has expired
- Why prior authorizations get delayed, and how to stop it
- Fringe benefits on certified payroll, explained properly
- How charge entry and claim submission work
Next step
Somebody to work your CO-45 queue
Full time, US hours, inside your system. Twenty minutes on a call is enough to tell whether it pays for itself.
Or write to ops@softhomeglobal.com

