OA 101 denial code

Claim adjustment reason code 101. Often reported as OA 101.

Predetermination estimate

Unofficial reference. This is our own plain-English explanation, not the official code text. Payer rules differ. Verify with the payer and the official X12 code list. AlphaPrefix is not affiliated with X12, CMS or any payer. Data last updated Nov 11, 2026.

What 101 means

The payer is showing the amount it expects to pay once the service is done or the claim is processed, not a payment.

This appears on a response to a predetermination or pre-treatment estimate. The figure is what the payer anticipates paying if the service is performed as described and the patient is still eligible.

No money moves with this code. The final amount can differ once the actual claim is submitted, because eligibility, benefits used and the services actually provided may change.

Group codes seen with 101

On a remittance, 101 comes after a group code. These are the ones it is most often reported with:

• OA 101 (Other Adjustment): Used for adjustments that are neither the provider's contractual write-off nor the patient's share. It often appears with coordination of benefits, for example when another payer already paid.

The payer chooses the group code for each adjustment, so the same reason code can appear with another group code on your remittance. Read the two together. More about group codes.

Common causes

• The provider submitted a predetermination request before treatment.
• The payer processed a claim as an estimate because it was flagged as a predetermination.
• A dental or high-cost service plan requires an estimate before treatment.

What to do next

1. Share the estimate with the patient and note that the final payment may differ.
2. Submit the actual claim after the service is performed, with the dates and codes actually provided.
3. Make sure claims for completed services are not sent with a predetermination indicator by mistake.

Related codes

• 119 (reason code) Benefit maximum reached