OA 100 denial code

Claim adjustment reason code 100. Often reported as OA 100 or PR 100.

Payment sent to the patient

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 100 means

The payer issued payment for this claim to the patient or subscriber instead of to the provider.

The claim was paid, but the check or transfer went to the member or another responsible party rather than to you. This usually happens when the payer did not have a valid assignment of benefits or the provider is out of network.

The patient now holds the payer's money for your service. Your collection path is with the patient, subject to your policies and any network or state rules.

Group codes seen with 100

On a remittance, 100 comes after a group code. These are the ones it is most often reported with:

• OA 100 (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.
• PR 100 (Patient Responsibility): The amount is assigned to the patient. Deductibles, coinsurance and copays are the everyday examples. Whether you can collect it still depends on your contract and the patient's plan.

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 claim did not show assignment of benefits to the provider.
• The provider is out of network and the payer pays members directly for such claims.
• The payer's records list a different payee for the member or plan.

What to do next

1. Confirm the claim indicated assignment of benefits and that a signed assignment is on file.
2. Contact the patient to collect the amount the payer sent them, following your financial policy.
3. Ask the payer whether it will honor assignment on future claims and how to update its records.

Related codes

• 111 (reason code) Covered only with assignment accepted