Occasionally there is a need to modify the President’s budget to recognize special circumstances that could not be foreseen when the President’s budget was transmitted to the Congress. Changes can only be requested by the President and these changes are called supplementals (for the current year) and amendments (for the next, or budget year). In addition, appropriations acts occasionally provide funds contingent upon the President taking further action to make them available (usually termed a “release”).
Office of Management and Budget