D.C. Mun. Regs. tit. 9, r. 9-419
By reason of privileges, exemptions, and immunities granted to certain foreign governments, those governments and their agencies (including embassies, legations, and commissions) may make purchases within the District of property or services for use in the conduct of their official activities if paid from their own funds without payment of the sales and use tax.
A letter of exemption with a separate identification number shall be issued by the District to each agency entitled to exemption under this section.
Each vendor shall keep a record of the following information with respect to sales to agencies which are exempt under this section:
Each vendor shall also keep a copy of the purchase order or a copy of the voucher accompanying the payment, and shall obtain the signature of the person making the purchase.
An employee of an exempt agency may not use the agency's exemption number to make purchases for his or her own personal use and are required to pay the District sales tax unless they are holders of a U.S. Department of State exemption card.
The Department of State determines, with the approval of the District, which diplomats and other employees of foreign governments are entitled to exemption from District sales and use taxes, and issues to each exempt person an exemption identification card designated "EXEMPTION CARD" (Form DS-816).
The exemption identification card shall bear the following:
By showing the exemption identification card to a vendor, the holder shall be entitled to make purchases in the District without paying the District sales or use tax.
When making a tax-free sale to a person holding an exemption identification card, a vendor shall exercise care to be certain of the identification of the purchaser by comparing the purchaser and his or her signature with the photograph and signature on the card.
No sales shall be made on a tax-free basis to any person other than one to whom an exemption card has been issued.
Vendors shall keep a record of sales to persons exempt under this section which shall include the following:
If the Department of State severs diplomatic relations with any country, the diplomats from that country will no longer be allowed to make tax-free purchases and their privileges will be revoked. Vendors will be notified from time to time by the Office of Finance and Revenue of revocations imposed under this section.
Sales to members of armed forces of foreign countries shall be subject to the District sales tax unless they hold a Department of State exemption identification card. District sales tax liability is not affected by Public Law 271, 81st Congress, which grants an exemption from customs duties and import taxes for foreign military personnel.
Vendors shall not accept the following means of identification as the basis for making tax-free sales:
D.C. Mun. Regs. tit. 9, r. 9-419