42 C.F.R. § 417.122
(a) Liability protection.
(1) Each HMO must adopt and maintain arrangements satisfactory to CMS to protect its enrollees from incurring liability for payment of any fees that are the legal obligation of the HMO. These arrangements may include any of the following:
(b) Protection against loss of benefits if the HMO becomes insolvent. The insolvency protection plan required under § 417.120(a) must provide for continuation of benefits as follows: