Budget reconciliation is a special parliamentary procedure of the United States Congress set up to expedite the passage of certain federal budget legislation in the Senate. The procedure overrides the Senate's filibuster rules, which may otherwise require a sixty-vote supermajority for passage. Bills described as reconciliation bills can pass the Senate by a simple majority of fifty-one votes or fifty votes plus the vice president's as the tie-breaker. The reconciliation procedure also applies to the House of Representatives, but it has minor significance there, as the rules of the House of Representatives do not have a de facto supermajority requirement. Because of greater polarization, gridlock, and filibustering in the Senate in recent years, budget reconciliation has come to play an important role in how the United States Congress legislates.

Budget reconciliation bills can deal with mandatory spending, revenue, and the federal debt limit, and the Senate can pass one bill per year affecting each subject. Congress can thus pass a maximum of three reconciliation bills per year, though in practice it has often passed a single reconciliation bill affecting both spending and revenue. Policy changes that are extraneous to the budget are limited by the Byrd rule, which also prohibits reconciliation bills from increasing the federal deficit after a ten-year period or making changes to Social Security. Reconciliation does not apply to discretionary spending, which is instead managed through the annual appropriations process.

The reconciliation process was created by the Congressional Budget Act of 1974 and was first used in 1980. Bills passed using the reconciliation process include the Consolidated Omnibus Budget Reconciliation Act of 1985, the Personal Responsibility and Work Opportunity Act of 1996, the Economic Growth and Tax Relief Reconciliation Act of 2001, the Health Care and Education Reconciliation Act of 2010, the Tax Cuts and Jobs Act of 2017, the American Rescue Plan Act of 2021, the Inflation Reduction Act of 2022, and the One Big Beautiful Bill Act.

Reconciliation is an optional part of the annual congressional budgetary process. Typically, the reconciliation process begins when the president submits a budget to Congress early in the calendar year. In response, each chamber of Congress begins a parallel budget process, starting in the Senate Budget Committee and the House Budget Committee. Each budget committee proposes a budget resolution setting spending targets for the upcoming fiscal year; in order to begin the reconciliation process, each house of Congress must pass identical budget resolutions that contain reconciliation instructions. Other committees then approve bills that meet the spending targets proposed by its respective budget committees, and these individual bills are consolidated into a single omnibus bill. Each house of Congress then begins consideration of its respective omnibus bills under its respective rules of debate.

The reconciliation process has a relatively minor impact in the House of Representatives, but it has important implications in the Senate. In contrast to most other legislation, senators cannot use the filibuster to indefinitely prevent consideration of a reconciliation bill, because Senate debate over reconciliation bills is limited to twenty hours. Thus, reconciliation bills only require the support of a simple majority of the Senate for passage, rather than the sixty-vote supermajority required to invoke cloture and defeat a filibuster. Senators could theoretically prevent passage of a reconciliation bill by offering an unending series of amendments in a process colloquially known as a "vote-a-rama," but, unlike the modern filibuster, senators introducing these amendments must stand up and verbally offer the amendments.

Though the reconciliation process allows a bill to bypass the filibuster in the Senate, it does not affect other basic requirements for the passage of a bill, which are laid out in the Constitution's Presentment Clause. The House and Senate still must pass an identical bill and present that bill to the president. The president can sign the bill into law or veto it, and Congress can override the president's veto with a two-thirds majority vote in both houses of Congress.

The Byrd Rule, named for Senator Robert Byrd, was adopted in 1985 and amended in 1990. The Byrd Rule defines a provision to be "extraneous"—and therefore ineligible for reconciliation—in six cases:

The Byrd Rule does not prevent the inclusion of extraneous provisions, but relies on objecting senators to remove provisions by raising procedural objections. Any senator may raise a procedural objection to a provision believed to be extraneous ("Byrdable"), which will then be ruled on by the presiding officer, customarily on the advice of the Senate parliamentarian: a vote of sixty senators is required to overturn their ruling. While the vice president (as president of the Senate) can overrule the parliamentarian, as of 2010^[update] this had not been done since 1975.^{[better source needed]}