1. "Discretionary" and "mandatory" dollars

My general understanding of the federal budget process in the USA is that:

  • discretionary spending must be "appropriated" by the House of Representatives every year, following ideas from Article I Sections 7 or 9 or something.
  • mandatory spending is not subject to this requirement.

2. This Congress can't bind a future Congress (?)

However, my layman's understanding of Congress's power also includes the notion that "this Congress can't bind a future Congress". Googling around has provided many instances of politicians and even law professors invoking this notion, but no authoritative source. Some (perhaps only weak) form of this principle must be true; otherwise this Congress could say "no new laws can be passed after 2030 except by a 4/5s majority in Congress" or whatever, effectively stripping future Congresses of all of their power.

3. So, "mandatory" for whom?

Thus I think my question is, for whom is the spending "mandatory"? Future Congresses? Could they just do a simple majority vote (assuming the President signs it) to alter "mandatory" spending? If so, is it really "mandatory"? And how would it then substantively differ from "discretionary" spending? Is "mandatory" really just an escape clause from requiring Appropriations by the House of Representatives?

  • 1
    You need both an Authorization bill and an Appropriations bill covering the funding use to pass to be allowed to spend money.
    – Jon Custer
    Nov 7, 2022 at 23:10

2 Answers 2


"Mandatory" spending means spending that takes place without passage of a new appropriation bill, but it may still be modified by Congress. The only truly mandatory spending categories that cannot be modified by future Congresses are interest on the national debt and certain multiple year contractual obligations (e.g. for naval ship building contracts).

"Discretionary" spending means spending that has to be appropriated each budget cycle. Without affirmative legislation, each budget cycle, it doesn't happen.

The distinction is important because the U.S. federal legislative process is frequently gridlocked with divided control with the President's political party (which has veto power), or with a division of partisan control between the two houses of Congress, each of which have veto power over the legislative process.

It takes the approval of both houses of Congress and the President to pass legislation except in the case of a rare veto override or a Senate and President approved treaty, which requires a two-thirds majority, and appropriations bills have to start in the U.S. House. If all three are not controlled by the same party, getting legislation passes as is necessary for discretionary spending, is challenging. So the status quo default of mandatory spending is hard to modify.

  • 1
    Which unit of law prevents Congress from passing a law that says ship builders shan't be paid? Nov 8, 2022 at 18:51
  • @user253751 The takings clause of the 5th Amendment to the U.S. Constitution as it has been interpreted by the courts, which states: "No person shall . . . be deprived of life, liberty, or property, without due process of law; nor shall private property be taken for public use, without just compensation."
    – ohwilleke
    Nov 8, 2022 at 21:35

My understanding is that "Discretionary" and "Mandatory" spending terms are not legal terms so much as political terms.

A future Congress certainly can legally choose to reduce spending on an essential service like Social Security checks, or interest payments on US Debt, but it would have significant social and political repercussions that leave Congress with very little choice but to continue the spending with at most minor changes.

If they did make substantial changes, the results could be disastrous. If Social Security payments were significantly cut, Senior Citizens could be unable to pay rent, or go hungry. If interest payments weren't reliable, the Credit of the USA would be demolished, and we would likely be in an instant Economic Depression.

This spending is termed "Mandatory".

The wiki article you linked to in your question even states:

Congress can only reduce the funding for programs by changing the authorization law itself. This requires a 60-vote majority in the Senate to pass.

So, Congress can change, reduce, or eliminate "Mandatory" spending, but it is more difficult to do so.

For more overview information: https://www.newamerica.org/education-policy/topics/federal-education-legislation-budget/federal-education-budget/federal-budget-process/mandatory-and-discretionary-spending/

  • Congress probably needn't act to reduce Social Security benefits; by law they can only be paid from the trust funds plus incoming taxes, and given current tax law and 'intermediate' actuarial assumptions about the future the OASI fund will be depleted in 2034 and taxes will pay only about 80% of scheduled benefits. See e.g. crsreports.congress.gov/product/pdf/RL/RL33514 and ssa.gov/oact/trsum . To avoid such most-likely-but-not-absolutely-certain reduction requires legislation, which there certainly will be much pressure for. Nov 8, 2022 at 15:13

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