An appropriations act provides money for spending, and no funds can be spent without it. An authorization is an act of Congress establishing a government program and defining the amount of money that it may spend. Authorizations may be for several years. However, the authorization does not actually provide the money that has been authorized; only an appropriations act can do that. Appropriations acts are almost always for a single fiscal year. Congress has its own rule that does not allow appropriations for programs that have not been authorized. However, appropriations frequently provide less money for programs than earlier authorizations.