45 CFR § 160.524 - Form, filing, and service of papers.
(2) Every pleading and paper filed in the proceeding must contain a caption setting forth the title of the action, the case number, and a designation of the paper, such as motion to quash subpoena.
(3) Every pleading and paper must be signed by and must contain the address and telephone number of the party or the person on whose behalf the paper was filed, or his or her representative.
(4) Papers are considered filed when they are mailed.
(b) Service. A party filing a document with the ALJ or the Board must, at the time of filing, serve a copy of the document on the other party. Service upon any party of any document must be made by delivering a copy, or placing a copy of the document in the United States mail, postage prepaid and addressed, or with a private delivery service, to the party's last known address. When a party is represented by an attorney, service must be made upon the attorney in lieu of the party.
(c) Proof of service. A certificate of the natural person serving the document by personal delivery or by mail, setting forth the manner of service, constitutes proof of service.