42 CFR § 424.64 - Payment after beneficiary's death: Bill has not been paid.
(1) The beneficiary has received covered Part B services furnished by a physician or other supplier.
(3) The bill has not been paid.
(c) To whom payment is made. In the situation described in paragraph (b) of this section, Medicare pays as follows:
(1) Payment to the supplier. Medicare pays the physician or other supplier if he or she -
(i) Files a claim on a CMS-prescribed form in accordance with the applicable requirements of this subpart;
(iii) Agrees in writing to accept the reasonable charge as the full charge for the services.
(2) Payment to a person who assumes legal obligation to pay for the services. If the physician or other supplier does not agree to accept the reasonable charge as full charge for the service, Medicare pays any person who submits to the carrier all of the following:
(i) A statement indicating that he or she has assumed legal obligation to pay for the services.
(ii) A claim on a CMS-prescribed form in accordance with the requirements of this subpart. (If a claim had been submitted by or on behalf of the beneficiary before he or she died, submission of another claim form is not required; a written request by the person seeking payment meets the requirement for a claim.)
(iii) An itemized bill that identifies the claimant as the person to whom the physician or other supplier holds responsible for payment. (If such an itemized bill had been submitted by or on behalf of the beneficiary before he or she died, submission of another itemized bill is not required.)
(iv) If the intermediary or carrier requests it, evidence that the services were actually furnished.