31 U.S.C. § 1537: Services between the United States Government and the District of Columbia government

the United States Government may provide services to the District of Columbia government; and the District of Columbia government may provide services to the United States Government. negotiated by officers and employees of the 2 governments; and approved by the Director of the Office of Management and Budget and the Mayor of the District of Columbia. Each agreement shall provide that the cost of providing the services shall be borne in the way provided in subsection (c) of this section by the government to which the services are provided at rates or charges based on the actual cost of providing the services. the District of Columbia government to officers and employees of the United States Government; and the United States Government to officers and employees of the District of Columbia government. costs incurred by the United States Government may be paid from appropriations available to the District of Columbia government officer or employee to whom the services were provided; and costs incurred by the District of Columbia government may be paid from amounts available to the United States Government officer or employee to whom the services were provided. When requested by the Director of the United States Secret Service, the Chief of the Metropolitan Police shall assist the Secret Service and the Secret Service Uniformed Division on a non-reimbursable basis in carrying out their protective duties under sections 3056 and 3056A of title 18.