42 CFR §422.520(a)

(a) Contract between CMS and the MA organization.

(1) The contract between CMS and the MA organization must provide that the MA organization will pay 95% of the “clean claims” within 30 days of receipt if they are submitted by, or on behalf of, an enrollee of an MA private fee- for- service plan or are claims for services that are not furnished under a written agreement between the organization and the provider. (Emphasis added.)

(2) The MA organization must pay interest on all clean claims that are not paid within 30 days in accordance with sections 1816(c)(2)(B) and 1842(c)(2)(B).