Question: What does the B3 on a patient's Medicare card stand for? Colorado Subscriber Answer: The B3 on a Medicare card stands for "Wife Age 65 or over; second claimant." You-ll find B3 placed as either a suffix or a prefix on the patient's Health Insurance Claim (HIC) number, which is usually a Social Security number (for example, 123-45-6789B3). Medicare organizes records using HIC numbers. So you must include them on all Medicare claim forms, related bills, documents, notices and any other communications dealing with a Medicare claim.