In the Federal budget, the ability of the Congress or the President under existing law to control outlays during a given fiscal year. Uncontrollable and relatively uncontrollable describe outlays, and the programs (such as Medicare) in which they occur, that cannot be increased or decreased without changes in existing substantive law. Such spending is usually the result of open-ended programs and fixed costs, like social security and veterans benefits, and payments due under obligations incurred or commitments made during prior years.