The U.S. Treasury divides all federal spending into three groups: mandatory spending,discretionary spending and interest on debt. Mandatory and discretionary spending account for more than ninety percent of all federal spending, and pay for all of the government services and programs on which we rely. Interest on debt, which is a much smaller amount than the other two categories, is the interest the government pays on its accumulated debt, minus interest income received by the government for assets it owns.
