D.C. Mun. Regs. tit. 17, § 1610
1610.1 When the Director proposes taking an action adverse to a licensee or applicant, having an effect listed in §1609.2, the Director shall first give to the licensee or applicant a written notice which shall contain at a minimum the following:
1610.2 The notice of proposed action may be served either personally or by certified mail, return receipt requested, directed to the person concerned at the last known residence or business address as shown by the records of the Department.
1610.3 The notice shall be deemed to have been properly served upon an applicant or licensee if a copy of the notice is left at the residence of the applicant or licensee with a person over the age of sixteen (16) years who then resides at the address.
SOURCE: Final Rulemaking published at 34 DCR 3165, 3170 (May 15, 1987).