42 CFR § 417.448 - Restriction on payments for services received by Medicare enrollees of risk HMOs or CMPs.
(a) Basic rule. Except for emergency and urgently needed services as defined in § 417.401, risk HMOs or CMPs are not required to make payments to or on behalf of certain Medicare enrollees, for any services received by the enrollees that are not provided -
(1) New Medicare enrollees;
(2) Nonrisk Medicare enrollees who convert to risk reimbursement; and
(3) Nonrisk Medicare enrollees who elect special supplemental benefit plans.
(c) End of restriction. The restriction of payments imposed by paragraph (a) of this section ends when a Medicare enrollee leaves the HMO's or CMP's geographic area for an extended period as defined in § 471.460(a)(2) and the HMO or CMP and the enrollee make arrangements for enrollment to continue as provided in § 417.460(a)(2)(iv).
(d) Timing. The effective date for the end of the restriction on payments, as discussed in paragraph (c) of this section is the first day of the first month following the month in which the enrollee notifies the HMO or CMP as required in § 417.436(a)(9), that he or she has left the HMO's or CMP's geographic area for an extended period.