Medicare AdvantageAdministrativeMedium impact
[California] UM Authorization ID format changes May 2026
Anthem BCBS·CA·Provider Bulletin
Effective date
May 15, 2026
We identified it
May 16, 2026
Summary
Anthem Blue Cross will expand UM Authorization ID format from 10 characters to 11 characters starting mid-May 2026. Billing teams must update system field lengths and validation rules to accommodate the new format to prevent automation failures and claim processing delays.
Action Required
Before May 15, 2026: IT and billing teams must update all systems that process UM Authorization IDs to accept 11-character (minimum) field lengths. Specifically: (1) Update billing software validation rules and database field definitions for UM ID fields; (2) Review automated claim submission interfaces and EDI integration points that consume UM IDs from response files; (3) Test system changes with sample 11-character IDs to ensure no automation delays or rejections; (4) Recommend increasing UM ID field length to 20 characters to prevent future disruptions. Failure to make these updates may result in claim processing delays or automation failures when the new format launches.