From the Summary: "Under the U.S. Constitution, Congress exercises the 'power of the purse.' This power is expressed through the application of several provisions. The power to lay and collect taxes and the power to borrow are among the enumerated powers of Congress under Article I, Section 8. Furthermore, Section 9 of Article I states that funds may be drawn from the Treasury only pursuant to appropriations made by law. The Constitution, however, does not prescribe how these legislative powers are to be exercised, nor does it expressly provide a specific role for the President with regard to budgetary matters. Instead, various statutes, congressional rules, practices, and precedents have been established over time to create a complex system in which multiple decisions and actions occur with varying degrees of coordination. As a consequence, there is no single 'budget process' through which all budgetary decisions are made, and in any year there may be many budgetary measures necessary to establish or implement different aspects of federal fiscal policy. This report describes the development and operation of the framework for budgetary decisionmaking that occurs today and also includes appendices that provide a glossary of budget-process-related terms and a flowchart of congressional budget process actions."
CRS Report for Congress, R46240
Congressional Research Service: https://crsreports.congress.gov/