Discretionary spending (vs. Mandatory spending)
What you should know about it
In general, when Congress decides how much it will spend, there are only certain programs they are required to make decisions about on an annual basis. These programs are discretionary, or in other words, the programs Congress has the most “discretion” over. Discretionary spending is usually divided into two categories: defense and non-defense, which is currently equal to about 36% of federal spending (Fiscal year 2011). The remainder of the budget is mandatory spending, which includes interest on the debt.
In contrast to discretionary programs where Congress must make annual spending decisions regarding amounts, the amount spent on mandatory programs is based on formulas already written into law. For example, the amount spent on Social security, the largest mandatory spending program, is not decided upon on an annual basis, but rather is calculated based on what the estimated number of beneficiaries and their required benefits. This is very different from the discretionary portion of the budget allocated to the National Institutes of Health for their research programs for example, where each year a dollar amount is budgeted based on available resources. Sometimes discretionary programs are cut; sometimes they are increased, depending on the priorities of Congress.
The key point is an overwhelming and growing share of the federal budget goes towards mandatory programs, which are essentially on auto pilot. Less and less of the budget goes towards discretionary programs, which includes programs that are critical to future economic growth, such as research, development and transportation, and also includes those that are actually spelled out as responsibilities of the federal government in the U.S. Constitution, such as Defense. Having a large and growing portion of the budget go towards mandatory spending, specifically interest is irresponsible and unsustainable.