Tax on fuel sold by United States agency in the District of Columbia.

When under authority of law gasoline or other motor vehicle fuel is sold by an agency of the United States within the District of Columbia, for use in privately-owned vehicles, such agency of the United States shall, by agreement with the Mayor of the District of Columbia, arrange for the collection of the tax herein authorized to be imposed, and for accounting to the Collector of Taxes of the District of Columbia for the proceeds of such tax collections.