42 C.F.R. § 408.80 – Basic rules.

(a) Sources of group payment. An employer, a lodge, union, or other organization may pay SMI premiums on behalf of one or more enrollees.
(b) Informal arrangement. Enrollees may turn over their premium notices to their employer, union, lodge, or other organization and that organization may send a single payment (with the premium notices attached so that the payments can readily be identified with the appropriate enrollees) to the CMS Premium Collection Center. Prompt payment is essential since SMI coverage terminates if premiums are not paid by the end of the grace period.
(c) Group billing arrangement. CMS may send a single notice for the premiums due from a group of enrollees if the following conditions are met:
1. (1) The group payer—
  1. (i) Uses funds other than the enrollees' to pay all or a substantial part of the premiums; or
  2. (ii) Deducts the premiums from periodic payments it makes to the enrollees in the group.
2. (2) The enrollee's rights are protected and enrollees are not required to pay the costs of having their premiums paid on a group basis.