OA 133 denial code
Claim adjustment reason code 133. Often reported as OA 133.
Service line still under review
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 .
What 133 means
The payer has not made a final decision on this service line yet, so it is being held pending further review.
This is a holding code, not a denial. The payer is telling you the line is under review and the outcome is not final. It is only used with group code OA.
When the review is finished, the payer is expected to reverse this line and send a corrected result. Do not adjust off or transfer the balance while the line carries this code; keep it open and watch for the follow-up remittance.
Group codes seen with 133
On a remittance, 133 comes after a group code. These are the ones it is most often reported with:
- OA 133 (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 payer pended the line for medical review or a records request.
- The service needs a pricing or coverage decision that has not been completed.
- A clinical or coding review is still open on the claim.
What to do next
- Leave the balance open and note the claim as pending rather than denied.
- Check the remittance and payer portal for any records request that needs a response.
- Follow up with the payer if no reversal and final result arrive within its normal review time.
- Post the final outcome when the reversal and corrected line come through.
Related codes
- 163 (reason code) Referenced attachment not received
- 16 (reason code) Missing information or billing error
Source
Official wording: X12 Claim Adjustment Reason Codes list. The explanation on this page is our own plain-English wording, not the X12 text.
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