D.C. Mun. Regs. tit. 3, § 1616
1616.1 Write-in candidacies shall be permitted for any office appearing on primary, general or special election ballot.
1616.2 To petition the Board for authorization to have pollwatchers and count observers on election day, a write-in candidate shall file with the Board, on or before 4:45 p.m. of the fourteenth (14th) day preceding the day of election, a Declaration of Candidacy and Affidavit of Qualifications on the form prescribed by the Board, and a petition authorizing pollwatchers and countwatchers pursuant to § 705 of this title.
1616.3 To be eligible to receive the nomination of a political party for public office, a write-in candidate shall be a duly registered member of the party nominated and shall meet all other qualifications required for election to the office, and shall declare his or her candidacy no later than 4:45 p.m. on the third (3rd) day immediately following the date of the election on a form or forms prescribed by the Board.
1616.4 To be eligible for election to public office, a write-in candidate shall be as follows:
(a) A duly registered elector;
(b) Meet all of the other qualifications required for election to the office; and
(c) Declare his or her candidacy no later than 4:45 p.m. on the seventh (7th) day immediately following the date of the election in which he or she was a candidate on a form or forms prescribed by the Board.
SOURCE: Final Rulemaking published at 36 D.C. Reg. 8364, 8371 (December 15, 1989); and further amended by Final Rulemaking published at 43 D.C. Reg. 1078, 1110 (March 1, 1996).