The federal budget process is a mixture of rules, timelines and norms that work together to influence policy decisions. It shapes how the President's goals and congressional preferences result in the spending and revenue levels in each year's budget.
Traditionally, the process begins with the Presidential budget submission, then moves to approval of the congressional budget, and finally to passage of appropriations bills. At any time along the way, Congress can pass other tax or spending bills. Sometimes procedural rules are put in place to increase the chance that those decisions are done in a fiscally responsible way -- such as pay-as-you-go (PAYGO) rules, discretionary spending caps, or the establishment of a special commission.