42 C.F.R. § 1006.3 – Service and fees.

(a) A subpoena under this part will be served by—
1. (1) Delivering a copy to the individual named in the subpoena;
2. (2) Delivering a copy to the entity named in the subpoena at its last principal place of business; or
3. (3) Registered or certified mail addressed to such individual or entity at its last known dwelling place or principal place of business.
(b) A verified return by the individual serving the subpoena setting forth the manner of service or, in the case of service by registered or certified mail, the signed return post office receipt, will be proof of service.
(c) Witnesses will be entitled to the same fees and mileage as witnesses in the district courts of the United States (28 U.S.C. 1821 and 1825). Such fees need not be paid at the time the subpoena is served.