(a) Mandatory service. Every document filed with the Office of Hearings shall be served upon all parties and participants to a proceeding, i.e., Complaint Counsel, respondent(s), and participants, and upon the Presiding Officer.

(b) Service of complaint, ruling, order, decision, or subpoena. Service of a complaint, ruling, order, decision, or subpoena may be effected as follows:

(1) By registered or certified mail. A copy of the document shall be addressed to the person, partnership, corporation or unincorporated association to be served at his or its residence or principal office or place of business; registered or certified; and mailed; or

(2) By delivery to an individual. A copy of the document may be delivered to the person to be served; or to a member of the partnership to be served; or to the president, secretary, or other executive officer, or a director of the corporation or unincorporated association to be served; or to an agent authorized by appointment or by law to receive service; or

(3) By delivery to an address. A copy of the document may be left at the principal office or place of business of the person, partnership, corporation, unincorporated association, or authorized agent with an officer, a managing or general agent; or it may be left with a person of suitable age and discretion residing therein, at the residence of the person or of a member of the partnership or of an executive officer, director, or agent of the corporation or unincorporated association to be served.

(c) Service of documents with prescribed response periods. When service of a document starts the running of a prescribed period of time for the submission of a responsive document or the occurrence of an event, the document shall be served as provided in paragraph (b) of this section.

(d) Service of other documents. All documents other than those specified in paragraph (c) of this section may be served as provided in paragraph (b) of this section, or by ordinary first-class mail, properly addressed, postage prepaid.

(e) Service on a representative. When a party has appeared by an attorney or other representative, service upon that attorney or other representative shall constitute service on the party.

(f) Certificate of service. The original of every document filed with the agency and required to be served upon all parties to a proceeding shall be accompanied by a certificate of service signed by the party making service, stating that such service has been made upon each party to the proceeding. Certificates of service may be in substantially the following form:

(g) Date of service. The date of service of a document shall be the date on which the document is deposited in the United States mail or is delivered in person.