This book provides a summary and legislative history of P.L. 111-139, focusing on the features of the Statutory Pay-As-You-Go (PAYGO) Act of 2010. PAYGO establishes a process intended to enforce a rule of budget neutrality on new revenue and direct spending legislation. As a budget enforcement tool, it is aimed at preventing, or at least discouraging, net deficit increases arising from the enactment of direct spending and revenue legislation. Any costs designated as emergencies are excluded from the scorecards, and significant costs associated with four specified categories of legislation may be excluded as well. The statutory PAYGO process does not address deficit increases, stemming from changes in direct spending or revenue levels, that are projected to occur under existing law.