42 CFR §408.60

1. (a)Premiums not deducted from monthly benefits under Subpart C of this part or paid by a State buy-in agreement must be paid by direct remittance to CMS or its agents, by or on behalf of the enrollee.
2. (b)Quarterly payment is preferred as more cost-effective, but monthly payment is accepted if the enrollee is unwilling or unable to make quarterly payments or is also paying hospital insurance premiums, which must be paid every month.
3. (c)CMS, directly or through its agents, sends quarterly or monthly premium bills and includes an addressed return envelope with the bill.
4. (d)The individual must—
   1. (1)Send a check or money order that is drawn payable to “CMS Medicare Insurance” and show the enrollee's name and claim number as it appears on the Medicare card; and
   2. (2)Return the bill with the check or money order in the preaddressed envelope.