42 CFR §411.52

1. (a)A conditional Medicare payment may be made in liability cases under either of the following circumstances:
   1. (1)The beneficiary has filed a proper claim for liability insurance benefits but the intermediary or carrier determines that the liability insurer will not pay promptly for any reason other than the circumstances described in § 411.32(a)(1). This includes cases in which the liability insurance carrier has denied the claim.
   2. (2)The beneficiary has not filed a claim for liability insurance benefits.
2. (b)Any conditional payment that CMS makes is conditioned on reimbursement to CMS in accordance with subpart B of this part.