CO-45 vs CO-97 vs PR-45

CO-45 is a contractual adjustment. The charge exceeds the amount your contract with that payer allows, and the difference is written off. It is not a denial and it is not billable to the patient.

Example: you bill $100 for a service. Your contracted rate with the payer is $80. The payer pays its share of the $80 and posts CO-45 on the remaining $20. That $20 is a write-off. You never send it to the patient.

The only time CO-45 is worth a second look is when the volume is climbing. That usually means your fee schedule or contract rates are loaded wrong in the system, or the contract was renegotiated and nobody updated the practice management software. Reconcile your loaded rates against the current contract once a quarter and the noise drops.

No. This is the one that trips people up. CO-97 does not mean the patient owes anything.

CO-97 means the benefit for this service is already included in the payment for another service that was adjudicated on the same claim. It's a bundling code. Common causes: a procedure that falls inside a surgical global period, or two codes where one is considered a component of the other under NCCI edits.

Because it's a CO code, it's a contractual write-off by default — not a patient charge. But it's often appealable when the bundling is wrong. If the two services were genuinely separate and distinct, the fix is usually the right modifier — 25 for a separate E/M on the same day, or 59 (or an X-modifier) to break an NCCI edit — and a corrected claim. Don't write it off automatically and don't bill the patient. Check whether the unbundling is justified first.

If you want patient copay, coinsurance, and deductible codes, those are PR-3, PR-2, and PR-1 — not CO-97.

This is the subtle one, and getting it wrong causes real problems.

Reason code 45 means "charge exceeds the fee schedule or maximum allowable." For a contracted, in-network claim, that amount belongs in group code CO — it's a write-off. So when it shows up as PR-45, the payer is saying the amount over the fee schedule is the patient's responsibility.

For an in-network provider, that's almost always a red flag, not a green light to bill. PR-45 on a contracted claim usually means one of three things: the payer processed you as out-of-network by mistake, your contract or fee schedule is loaded incorrectly on their end, or the member's plan was misidentified. The right move is to research why it came back PR before touching the patient's statement. Balance-billing an in-network patient for an over-fee-schedule amount is exactly the kind of thing that draws complaints and, under the No Surprises Act, can be a compliance issue.

PR-45 is legitimately billable in one situation: the service really was out-of-network and no surprise-billing protection applies. Even then, check your state's balance-billing rules and the federal No Surprises Act before you send it, because a lot of what used to be billable no longer is.

• CO-45 — over the contracted rate. Write it off. Watch the volume for fee-schedule loading errors.
• CO-97 — bundled into another service. Contractual by default, but appeal with the right modifier when the services were separate. Never the patient's charge.
• PR-45 — over the fee schedule, flagged as patient responsibility. On an in-network claim, treat it as a processing error and investigate before billing anyone. Only bill when the claim was truly out-of-network and no surprise-billing protection applies.

Read the group code first, then the number. That one habit prevents both the lost write-offs and the improper patient bills.