Traditional MedicareAdministrativeHigh impact
Guidance for Medicare/Medi-Cal Crossover Claim Submission on the Paper CMS-1500
Medi-Cal·CA·Claims & Billing
Effective date
Jul 21, 2026
We identified it
Jul 22, 2026
Summary
California Medi-Cal has issued updated guidance for submitting Medicare/Medi-Cal crossover claims on paper CMS-1500 forms. Providers must now submit crossover claims directly to the California MMIS Fiscal Intermediary at a specific Sacramento address, with strict formatting requirements for key CMS-1500 fields (Boxes 1, 1A, 9A, and 11C) and must attach a corresponding Medicare Remittance Notice with each submission. Claims not meeting these requirements will be returned.
Action Required
Effective immediately (July 21, 2026): Billing team must implement the following changes: (1) Update all CMS-1500 crossover claim submission procedures to route claims to the California MMIS Fiscal Intermediary at P.O. Box 15700, Sacramento, CA 95852-1700 instead of any previous addresses; (2) Modify billing system templates and provider instructions to ensure CMS-1500 Box 1 has 'X' marked in BOTH Medicare and Medicaid fields; (3) Require Box 1A to contain Medicare ID number; (4) Require Box 9A to contain Medi-Cal ID in either 14-digit or 9-digit CIN format; (5) Require Box 11C to contain Medicare Carrier Code; (6) Update claim submission workflows to mandate a separate copy of the Medicare Remittance Notice (MRN) with every crossover claim; (7) Ensure all Medicare-allowed lines from the MRN are included on the crossover claim and match exactly; (8) Train billing staff that Medicare-denied lines on the same claim/MRN cannot be paid via crossover; (9) Clarify that Medicare Advantage/HMO members require straight Medi-Cal claims with EOB instead of crossover format. Failure to comply will result in claim denials and returns. Affected providers include all practices billing Medicare/Medi-Cal crossover claims in California.