D.C. Mun. Regs. tit. 9, r. 9-445
In addition to the specific exemptions provided in the Act (D.C. Code § 47-2005) , gross receipts from the types of sales set forth in this section shall be exempt from the tax imposed by the Act.
For the purposes of sales to the District or Federal governments under D.C. Code § 47-2005(1), vendors may treat as nontaxable the receipts from, and shall be relieved from the duty of collecting their reimbursement for tax on, sales to the United States and to the District of Columbia on any purchase order made by any authorized purchasing officer or by contract in which either the United States or the District of Columbia or any instrumentality of either Government is a party.
Sales of publications of the United States and District governments and any instrumentality of either government shall be exempt from the tax.
D.C. Mun. Regs. tit. 9, r. 9-445