CMS CR 14553: Part A MSP claims will reject, RTP, or suspend on named CARCs from January 1, 2027

CMS issued Change Request 14553 on August 21, 2026, as Transmittal 13932 (Pub 100-20 One-Time Notification). The subject is A/B Medicare Administrative Contractors (MACs) Part A and the Fiscal Intermediary Shared System (FISS) processing Medicare Secondary Payer (MSP) claims that carry certain Claim Adjustment Reason Codes (CARCs).

EFFECTIVE DATE: January 1, 2027 (date of service unless otherwise specified). IMPLEMENTATION DATE: January 4, 2027. CMS released the provider-facing MLN Matters article MM14553 on September 4, 2026.

This is Part A MSP claim processing, not a CMS-HCC map change and not the live October 2026 MPFSDB CR 14588 fee-schedule story.

What CR 14553 changes

The CR says many MSP CARCs were previously automated, denied, or suspended for manual review. After discussions with A/B MACs Part A and FISS, CMS is directing which CARCs process through automation without manual intervention, which continue to suspend, and which reject.

Business requirement 14553.1 tells FISS and A/B MACs Part A to update their systems to process the CARCs found on MSP claims as discussed in the MSP analysis calls. Policy in the CR: A/B MACs Part A and FISS must use the CARC adjustments on the 837 when adjudicating MSP claims.

MM14553 tells billing staff the operational rule in plain language: your MAC processes several CARCs systematically, and CMS is directing which CARCs process automatically and which MACs will suspend for manual review or deny.

Copy the primary payer CAS onto the 837

MSP policy tells MACs and shared systems what to consider when they process MSP claims, including primary payer adjustments that explain why the primary payer did not fully pay the billed amount.

Primary payers and Medicare report payment adjustments in either the claim adjustment segment (CAS) on the 835 Electronic Remittance Advice or a paper remittance. MM14553 says you must take the CAS adjustments on the 835 and report them unchanged on the 837 when you send a claim to Medicare for secondary payment. Part A MACs and claims processing systems use those adjustment amounts and CARCs to determine payment on MSP claims.

If the remittance shows a CARC that Medicare cannot process for secondary payment, the MAC can return the claim. The remittance advice identifies the reason. You then correct and, in many cases, resubmit to the primary payer or to Medicare.

Reject, RTP, and suspend buckets that the CR names

The business-requirement tables name specific CARCs and Part A reason codes. This page lists the CARC values the CR prints. It does not invent X12 long definitions for those codes.

For BR 14553.6, Part A MACs shall include adjustment reason 276 and MSN 16.32 on MAP 1232. For BR 14553.7, they shall also include group code CO with adjustment reason 276 and MSN 16.32.

FISS shall reactivate reason code 31658 (tied to the RTP list that includes CARC 7). BR 14553.9.1 says FISS shall make the reason codes overrideable.

CARCs turned off so MSP claims can process

Business requirement 14553.10 tells A/B MACs Part A and FISS to turn off the following reason codes permanently for the applicable CARCs so MSP claims can process:

Those are the automation path. The CR turns those reason codes off so the named CARCs no longer stop the claim the old way.

What this is not

It is not a CMS-HCC, V28, or RADV documentation change. CARC handling on an MSP secondary claim does not rewrite risk-adjustment diagnosis rules. If the question is risk scores, use ICD-10 to HCC for the model year you are coding.

It is not the live October 2026 SNF consolidated billing HCPCS update. Different CR, different file set.

It is not the live October 2026 MPFSDB CR 14588 physician fee schedule database story.

Look up official procedure and diagnosis descriptors in the encoder or the code book when the MSP claim also depends on a code change. This page stays on the CARC processing rules CMS printed.