CMS explains January Medicare Secondary Payer adjustment-code processing
Oct 4, 2026 edition · GC-2026-0031 · Published 2026-10-04 · Version 2 · Final
January MSP processing changes distinguish automatically processed adjustment codes from manual review or denial, with original primary-payer adjustments carried into secondary claims.
What happened
CMS released MM14553 on September 4, 2026 for the August 21 change request governing certain Medicare Secondary Payer claim adjustment reason codes. The Part A MAC/FISS processing changes are effective January 1, 2027 and implement January 4. Some codes process systematically, while others suspend for manual review or deny. MACs may return claims Medicare cannot process and identify the reason on remittance advice, allowing correction and, where appropriate, resubmission to the primary payer or Medicare. The article does not say every returned claim will become payable.
Primary payers and Medicare report adjustments through the CAS segment of an 835 electronic remittance or paper advice. Providers must transfer CAS adjustments from the 835 unchanged to the 837 institutional claim submitted for Medicare secondary payment. MACs and their systems use the adjustment amounts and CARCs to calculate payment. Mapping software must therefore preserve the primary payer's information rather than recode an adjustment simply to force automatic processing. The January dates concern the processing change; they do not erase existing coordination-of-benefits or accurate secondary-claim requirements.
Scope and timing
- Authority status
- Final
- Applicability
- Operationally relevant
- Audience
- Health systems, Provider networks
- Jurisdiction
- Federal
- Affected functions
- Revenue Cycle, Coding, IT
- Responsible owner
- Revenue Cycle
- Recorded date
- 2027-01-01
- Date type
- effective
Why it matters
Incorrect adjustment mapping can distort secondary payment or cause returns. Manual-review and denial paths need ownership as well as automated-claim testing.
Recommended action
Validate 835-to-837 adjustment mapping and returned-claim correction routes with the MAC, including manual-review cases. Track January 1 effectiveness separately from January 4 implementation.
Sources
- MM14553, Medicare Secondary Payer claim processingOfficial · CMS · 2026-09-04 · Source review 2026-09-06
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