D.C. Mun. Regs. tit. 17, r. 17-2713
Any notice required by this chapter may be served either personally by the Director, or his or her agent, or by certified mail, return receipt requested, directed to the person concerned at his or her last known residence or business address as shown by the records of the Department of Consumer and Regulatory Affairs. Notice shall be served at least fifteen days prior to the hearing.
If notice is served personally, it shall be considered to have been served at the time when delivery is made to the person concerned. If notice is served by certified mail, it shall be considered to have been served on the date borne upon the return receipt showing delivery of the notice to the person concerned or refusal of the person concerned to receive notice.
If the person concerned is no longer at the last known address as shown by the records of the Department of Consumer and Regulatory Affairs and no forwarding address is available, the notice shall be considered to have been served on the date the return receipt bearing the notification is received by the Director.
If a person scheduled for a hearing does not appear and no continuance has been or is granted, the Board shall hear the evidence of the witnesses as may have appeared, and the Board may proceed to consider the matter and render a decision on the basis of evidence before it.
D.C. Mun. Regs. tit. 17, r. 17-2713