FY 2009 U.S. federal budget

Background
Funding for the government is provided by Congress under Article I, Section 9, Clause 7 of the Constitution. This is the "purse strings power" and there are no exceptions to it. Absent appropriations made by law, no operations by the government may take place: government employees may not work without pay and those who would contract with the government may not "volunteer" their goods or services.

Funding for government employees salaries and wages(including the President) is provided in "one year" funds which expire at the end of a fiscal year. While Congress may pass "continuing resolutions" providing some interim funding where appropriations are not timely enacted, in the absence of such continuing resolutions no government employee may work.