D.C. Mun. Regs. tit. 22, r. 22-B3109
Any notice required by this chapter may be served either personally or by certified mail, return receipt requested, directed to the applicant or licensee at the last known address as shown by the records of the Department of Consumer and Regulatory Affairs.
If notice is served personally, it shall be deemed by the Director to have been served at the time when delivery is made to the applicant or licensee.
If notice is served by certified mail, it shall be deemed by the Director to have been served on the date written or stamped upon the return receipt showing delivery of the notice to the applicant or licensee, or refusal of the applicant or licensee to receive the notice.
In the event that the applicant or licensee 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 deemed by the Director to have been served on the date the return receipt bearing the notification is received by him or her.
If an applicant or licensee scheduled for a hearing does not appear and no continuance has been or is granted, the Director may hear the evidence of the witnesses who have appeared, and the Director may proceed to consider the matter and render a decision on the basis of the evidence available.
D.C. Mun. Regs. tit. 22, r. 22-B3109