Mandatory Spending - Not Necessarily

Congress essentially classifies federal spending as either discretionary or mandatory.

Discretionary spending is not fixed or guaranteed and is subject to annual appropriations. Since it's discretionary, in theory anything can be added or eliminated. In practicality, only a small percentage of discretionary spending is actually subject to change. Consider regulatory agencies like the Food and Drug Administration (FDA) or Securities and Exchange Commission (SEC). These agencies might make some changes by adding staff, eliminating programs or shifting resources, but they can't dramatically alter operations every year. Therefore, most discretionary expenditures are somewhat fixed.

Mandatory spending doesn't require annual appropriations and is essentially on auto-pilot. The spending is typically based on some eligibility criteria and it expenditure is made as long as the criteria is met. Social Security, Medicare and Medicaid are the three largest types of mandatory spending. Although Congress treats mandatory expenditures as beyond of their control, all mandatory spending can be changed or eliminated by passing new legislation. For example, Congress can raise the age of eligibility for Social Security retirement benefits from 67 to 70 by passing a new law, which would cause Social Security spending to decrease for the year. Politically it may be difficult, but it can be done.

Although nearly two-thirds of all current federal spending is classified as mandatory and on auto-pilot. Congress has the Constitutional power to change any and all federal spending, if they choose; both discretionary and mandatory. In short... Congress controls all spending and balancing the budget may not be easy, but it can be done.