31 U.S.C. § 1301: Application

Appropriations shall be applied only to the objects for which the appropriations were made except as otherwise provided by law. The reappropriation and diversion of the unexpended balance of an appropriation for a purpose other than that for which the appropriation originally was made shall be construed and accounted for as a new appropriation. The unexpended balance shall be reduced by the amount to be diverted. is for rivers and harbors, lighthouses, public buildings, or the pay of the Navy and Marine Corps; or expressly provides that it is available after the fiscal year covered by the law in which it appears. A law may be construed to make an appropriation out of the Treasury or to authorize making a contract for the payment of money in excess of an appropriation only if the law specifically states that an appropriation is made or that such a contract may be made. no amount may be transferred from an appropriation account for the Departments of Labor, Health and Human Services, and Education except as authorized in this or any subsequent appropriation Act, or in the Act establishing the program or activity for which funds are contained in this Act [see Tables for classification]; no department, agency, or other entity, other than the one responsible for administering the program or activity for which an appropriation is made in this Act, may exercise authority for the timing of the obligation and expenditure of such appropriation, or for the purpose for which it is obligated and expended, except to the extent and in the manner otherwise provided in sections 1512 and 1513 of title 31, United States Code; and no funds provided under this Act or subsequent Departments of Labor, Health and Human Services, Education, and Related Agencies Appropriations Acts shall be available for the salary (or any part thereof) of an employee who is reassigned on a temporary detail basis to another position in the employing agency or department or in any other agency or department, unless the detail is independently approved by the head of the employing department or agency.”