42 CFR §417.404

1. (a)In order to contract with CMS under the Medicare program, an entity must—
   1. (1)Be determined by CMS to be an HMO or CMP (in accordance with §§ 117.142 and 417.407, respectively); and
   2. (2)Comply with the contract requirements set forth in subpart L of this part.
2. (b)CMS enters into or renews a contract only if it determines that action would be consistent with the effective and efficient implementation of section 1876 of the Act.