News & Information. CMS - How to Understand Medicare's ID Numbers (HIC or HICN) A HIC number (HICN) is a Medicare beneficiary’s identification number. Also, remember when billing, ALWAYS use the name as it appears on the patient's Medicare card. Both CMS and the Railroad Retirement Board (RRB) issue Medicare HIC numbers. The format of a HIC number issued by CMS is a Social Security number followed by an alpha or alphanumeric Beneficiary Identification Code (BIC). RRB numbers issued before 1964 are six-digit numbers preceded by an alpha character.