Changes to the Three-Character Prefix on Member ID Cards

Posted March 25, 2019

Blue Cross and Blue Shield member ID numbers usually begin with a three-character prefix. Prior to April 2018, the prefixes included letters only. To ensure there are enough prefixes to support current and future business needs, the prefixes may now be alphanumeric.

Quick reminders:

  • If a Blue Cross and Blue Shield member’s ID number does not have a three-character prefix, make sure you request their most current identification card.
  • Three-character member ID prefixes may now have both letters and numbers.
  • Member ID cards that have letters-only prefixes are still valid.
  • The three-character prefix is always followed by the rest of the member’s ID number.
  • Include the entire member ID number, with the prefix, on all correspondence and claims.
  • Do not omit, randomly select or substitute a different three-character prefix.
  • Some Blue Cross and Blue Shield member ID prefixes may have less than three characters. Federal Employee Program® (FEP®) members, for example, have a single-letter prefix.