((a)) ** Transmittal of special message** Whenever the President, the Director of the Office of Management and Budget, the head of any department or agency of the United States, or any officer or employee of the United States proposes to defer any budget authority provided for a specific purpose or project, the President shall transmit to the House of Representatives and the Senate a special message specifying—
((1)) the amount of the budget authority proposed to be deferred;
((2)) any account, department, or establishment of the Government to which such budget authority is available for obligation, and the specific projects or governmental functions involved;
((3)) the period of time during which the budget authority is proposed to be deferred;
((4)) the reasons for the proposed deferral, including any legal authority invoked to justify the proposed deferral;
((5)) to the maximum extent practicable, the estimated fiscal, economic, and budgetary effect of the proposed deferral; and
((6)) all facts, circumstances, and considerations relating to or bearing upon the proposed deferral and the decision to effect the proposed deferral, including an analysis of such facts, circumstances, and considerations in terms of their application to any legal authority, including specific elements of legal authority, invoked to justify such proposed deferral, and to the maximum extent practicable, the estimated effect of the proposed deferral upon the objects, purposes, and programs for which the budget authority is provided.
((b)) ** Consistency with legislative policy** Deferrals shall be permissible only—
((1)) to provide for contingencies;
((2)) to achieve savings made possible by or through changes in requirements or greater efficiency of operations; or
((3)) as specifically provided by law.
((c)) ** Exception** The provisions of this section do not apply to any budget authority proposed to be rescinded or that is to be reserved as set forth in a special message required to be transmitted under .section 683 of this title