What Does M Mean At The End Of A Medicare Number? 
The letter M at the end of a Medicare number means that the Medicare patient is enrolled in Part B but is not insured for Medicare Part A . The description for M is `` Uninsured Premium Health Insurance Benefits -LRB- Part A -RRB- '' . There is also a Medicare designation of M1 which means `` Uninsured - Qualified for but refused Health Insurance Benefits -LRB- Part A -RRB- '' . 