# OA 23 Denial Code: Prior Payer Adjustments and the Balance

> OA 23 shows how a prior payer's payment or adjustment changed what the secondary payer owes. Reconcile it with the primary remit, then bill the balance.

Source: https://webillhealth.com/oa-23-denial-code/  
Publisher: WeBill Health  
Last updated: November 4, 2026

Denial code

## OA 23 adjustment, the secondary balance reconciled

OA 23 shows how a prior payer changed the amount owed. Read it as math to reconcile, not a denial.

[Request a Revenue Defense Audit](https://webillhealth.com/revenue-defense-audit/request/)

OA 23 is an adjustment, not a rejection. It appears on a secondary claim remit to show the impact of what the prior payer paid or adjusted. The work is to reconcile that amount against the primary remit and bill whatever is still owed.

* What CARC 23 says
The impact of prior payer(s) adjudication including payments and/or adjustments. [X12 reason codes](https://x12.org/codes/claim-adjustment-reason-codes)
* Group code OA
Other Adjustment. [X12 group codes](https://x12.org/codes/claim-adjustment-group-codes)
* How Medicare reports it
Medicare reports a further adjustment from a prior payer’s payment or adjustment with Group Code OA and CARC 23. [CMS, Transmittal 1318](https://www.cms.gov/files/document/r1318otnpdf)
* What it shows
Medicare reports only the part of the prior payer’s adjudication that affects its own payment and adjustments. [CMS, Transmittal 1318](https://www.cms.gov/files/document/r1318otnpdf)

## In the official words

> The impact of prior payer(s) adjudication including payments and/or adjustments

[X12](https://x12.org/codes/claim-adjustment-reason-codes)

> Medicare should report only the part of previous payer’s adjudication that impacts Medicare calculation of payment and adjustments.

[Centers for Medicare & Medicaid Services](https://www.cms.gov/files/document/r1318otnpdf)

## Read OA 23 as the effect of the first payer

X12 says to use CARC 23 only with Group Code OA. For Medicare, CMS instructs contractors to report OA 23 once, as the total impact of the prior payer, and not to repeat everything the prior payer did. That detail stays on the prior payer’s own remittance. [X12 reason codes](https://x12.org/codes/claim-adjustment-reason-codes) [CMS, Transmittal 1318](https://www.cms.gov/files/document/r1318otnpdf)

The secondary remit will not match the primary remit line for line. CMS words the reason this way: only the primary amount that actually impacted the secondary payment is reported, and in many cases that impact is less than the actual primary payment. The transmittal dates from 2013 and took effect in 2014, so read it as the Medicare rule behind today’s remits.

## How to clear an OA 23 line

1. Pull the primary payer remittance and the secondary remittance for the same claim.
2. Match the primary payment and adjustments to the impact amount on the secondary remit.
3. If the two agree, post the OA 23 amount as an adjustment and move on.
4. If they do not agree, go back to the claim and check that it carried the primary payer’s identity and payment information. X12 says secondary payment cannot be considered without them. Correct the claim if it did not.
5. Bill any patient responsibility the secondary remit still reports under Group Code PR.

CMS instructs Medicare contractors to report remaining patient responsibility with Group Code PR. [CMS, Transmittal 1318](https://www.cms.gov/files/document/r1318otnpdf) [X12 remark codes](https://x12.org/codes/remittance-advice-remark-codes)

## Stop OA 23 confusion before it starts

Post the secondary remit with the primary remit beside it. The primary payer’s payment and adjustments should be in the account before the secondary claim is reconciled. If the primary remit is missing, the OA 23 amount cannot be checked.

WeBill Health maintains internal payer rule libraries organized by specialty and by carrier, built and updated by people who work claims in your specialty every day. Every claim receives Human Expert Review against them before it goes out.

## Sources

* [X12 reason codes](https://x12.org/codes/claim-adjustment-reason-codes)
* [X12 group codes](https://x12.org/codes/claim-adjustment-group-codes)
* [CMS, Transmittal 1318](https://www.cms.gov/files/document/r1318otnpdf)
* [x12.org, remittance advice remark codes](https://x12.org/codes/remittance-advice-remark-codes)

## Denial Defense 2.0

Root cause denial work that closes the documentation gaps behind repeat denials before they disrupt your revenue cycle.

**98%**

clean claim rate

**40%**

A/R reduction within 90 days

**500+**

payer rulesets in our rule libraries

[See Denial Defense 2.0](https://webillhealth.com/denial-defense-2-0/)

## Related denial codes

These codes often appear beside OA 23 or clear the same way.

* [CO 16](https://webillhealth.com/co-16-denial-code/)
* [CO 22](https://webillhealth.com/co-22-denial-code/)
* [CO 45](https://webillhealth.com/co-45-denial-code/)

See every code on [Denial Codes Explained: What Each Means and How to Clear It](https://webillhealth.com/denial-codes/). For state by state Medicaid enrollment, see [Medicaid provider enrollment by state](https://webillhealth.com/medicaid-provider-enrollment/).

Reviewed by [Tyler Nguyen](https://webillhealth.com/tyler-nguyen/), Denial Defense Manager, on November 4, 2026. Facts verified November 1, 2026.

## Find the denials that keep coming back

The Revenue Defense Audit is a free, forensic review of your claims and A/R by the team that would work your account. It maps your denial patterns by payer and code, with the root cause behind each one.

[Check my Revenue Defense Score](https://webillhealth.com/revenue-defense-score/?specialty=geriatrics) for the denial exposure in your specialty.

[Request a Revenue Defense Audit](https://webillhealth.com/revenue-defense-audit/request/)

WeBill Health is a specialty focused revenue cycle management partner for independent practices. Request a Revenue Defense Audit at https://webillhealth.com/form/