Congress and the President may have agreed on a two-year, budget earlier this fall, but the nation is not out of the fiscal woods yet. They’ve got until midnight Friday to assign money to federal agencies and programs, or those agencies will run out of money.

The federal budget has been in the works since the President first submitted his spending request to Congress as required by law on the first Monday of February. His budget proposal is based in part on federal agencies’ requests for the upcoming year. In a simpler world, Congress would look at the President’s ideas, write up a budget and send it back to the President for his signature, end of story at least for the upcoming fiscal year.

But because the process isn’t that simple, we are now into December and the budget details are still not worked out. Congress needs to pass a spending bill to fill in the blanks left over from the overall budget agreement. Lawmakers have hundreds of pages of line items to fill which still need the President’s signature before the budget can be considered complete.

The budget process can get hung up between the asset and liability side of the ledger, but according to nationalpriorities.org, other factors such as the state of the economy, party politics and differing economic philosophies can impact how those line items are filled in. If lawmakers fail to fill in these blanks by the December 11th deadline, they can either pass a short-term spending bill just to get by until complete passage of the bill or they can allow the government to go into “shutdown” mode.

This sounds a little scary, but it’s not, at least for most of us. A government shutdown starts with what’s called a “furlough” of non-essential government workers, which basically means involuntary layoffs. During a government shutdown, non-essential agency services and activities are also put on hold.

And government shutdowns are not necessarily a rare occurrence. A Wikipedia compilation lists shutdowns during the presidencies of Gerald Ford (one, lasting ten days,) Jimmy Carter (five, lasting eight to 18 days,) Ronald Reagan (funding gaps with technical shutdowns lasting less than 48 hours or over weekends,) George H. W. Bush (one, causing a weekend shutdown,) Bill Clinton (two full government shutdowns during 1995 and 1996 lasting 5 and 21 days respectively.)

Under the current administration, the United States federal government shutdown in 2013, from October 1 to 16, 2013.

To learn more about the federal budget process, read “President and Congress Gearing up for Budget Battle.”