While the PAYGO principle can exist as an informal norm or an internal congressional rule, it was formally re-established as federal law through the Statutory Pay-As-You-Go Act of 2010. This Act was signed into law by President Barack Obama on February 12, 2010, as Title I of Public Law 111-139 (H.J.Res. 45) and is codified at 2 U.S. Code § 931 et seq. Its stated purpose was to reestablish a statutory procedure to enforce a rule of budget neutrality on new revenue and direct spending legislation.
The legislative path of the Act saw it introduced in the House of Representatives by then-Majority Leader Steny Hoyer. It was eventually attached in the Senate to legislation raising the federal debt limit and passed largely along party lines, with a majority of Democrats supporting it and a majority of Republicans opposing it. This attachment to must-pass debt limit legislation is a common legislative tactic but also underscores the high stakes involved in both fiscal rules and debt management.
The Statutory PAYGO Act of 2010 applies specifically to new legislation that affects direct spending (also known as mandatory or entitlement spending) and revenues. If a new law is projected to increase direct spending or decrease revenues, it must be offset by corresponding spending cuts or revenue increases so as not to increase the deficit.
However, the law includes several key exclusions, significantly narrowing its effective scope:
https://govfacts.org/explainer/understanding-pay-as-you-go-paygo-vs-statutory-paygo-in-federal-budgeting/