OA-91: Dispensing Fee Adjustment

What Does OA-91 Mean?

OA-91 is uncommon and typically appears in coordination of benefits scenarios where the dispensing fee adjustment does not fall into standard contractual or patient responsibility categories. It may also appear when the dispensing fee adjustment is informational — for example, when a primary payer adjusts the dispensing fee and the remaining balance is forwarded to a secondary payer for consideration.

When CARC 91 appears on your remittance, the payer is telling you that the dispensing fee you billed has been reduced to align with their fee schedule or your contracted rate. The claim itself was processed — the medication and associated charges were adjudicated — but the dispensing fee component was adjusted downward. This is one of the most routine adjustment codes in pharmacy and dispensing-provider billing.

The adjustment typically reflects the gap between your billed dispensing fee and the payer's allowed amount for that specific medication and dispensing scenario. Under most provider contracts, you agreed to accept the payer's dispensing fee schedule, making this a legitimate contractual write-off rather than a denial requiring action. The amount shown as the CARC 91 adjustment is the difference between what you billed and what the payer's fee schedule allows.

However, not every CARC 91 is a straightforward fee schedule adjustment. If you used an incorrect billing code, submitted incomplete documentation, or dispensed a medication not on the payer's formulary, the adjustment may be larger than expected or may zero out the dispensing fee entirely. In these cases, the root cause is a billing or formulary issue that needs to be corrected rather than simply written off.

How to Resolve

Verify the dispensing fee adjustment matches your contracted rate, then post the write-off or correct the billing error and resubmit.

1. Check for secondary insurance Verify whether the patient has a secondary payer that should receive the claim for the remaining dispensing fee balance after the primary payer's OA-91 adjustment.
2. Submit to secondary payer if applicable If a secondary payer exists, file a claim with the primary ERA attached showing the OA-91 adjustment. The secondary payer will adjudicate the remaining balance.
3. Contact the payer for clarification If no COB scenario applies, contact the payer to understand why OA was used instead of CO. Request reprocessing with the correct group code if needed.

How to Prevent OA-91

• Collect and verify all insurance coverage details during patient registration to ensure proper COB sequencing for dispensing claims
• Submit dispensing claims to the primary payer first and wait for the remittance before filing with secondary payers

Also Filed As

The same CARC 91 may appear with different Group Codes:

Related Denial Codes