Government spending: Unless lawmakers avert the so-called sequester, a series of automatic cuts will reduce the budgets of most federal agencies and programs by 8% to 10%.
But that doesn't necessarily mean those cuts would have to occur immediately, according to a former official with the Office of Management and Budget.
Both the White House budget office and federal agencies themselves will have some latitude to postpone the cuts from occurring "for several weeks if necessary," added OMB Watch, a group that monitors the federal budget.
The cuts, if not reversed, would likely lead to unpaid furloughs of federal workers. Agencies must give at least 30 days' notice to employees for a furlough that would last less than 22 work days; 60 days' notice is required for longer furloughs. So far, federal workers have been told to report to work as scheduled on Jan. 2, the day the spending cuts formally kick in.
U.S. economy: Economists expect the U.S. economy would fall into a recession if Congress does nothing to avert the fiscal cliff and lets it stay in effect.
Specifically, the CBO forecasts a drop of 0.5% in real gross domestic product and a 9.1% unemployment rate by the end of next year.
On the bright side, no one expects that Congress would let all fiscal cliff measures have their way with the economy for an extended period.
But there could still be an economic hit if lawmakers push the country over the fiscal cliff temporarily and then pass a fallback deal that primarily averts just some of the tax increases.
For example, Congress may end up passing only a stopgap measure that does not address the automatic spending cuts or raise the country's debt ceiling. In that case, economic growth could be dragged down somewhat in the first half of next year, according to economists at Goldman Sachs.
And remember that the economy is already going to be dragged back somewhat by the expected expiration of the payroll tax cut.
Unemployment benefits: A federal extension of unemployment benefits is set to expire. If Congress does not renew it, workers who lost their jobs after July 1, 2012, will only receive up to 26 weeks in state unemployment benefits, down from as many as 73 weeks in state and federal benefits that have been available in 2012.
As a result, more than 2 million of the long-term unemployed will run out of benefits at the end of this year, according to the National Employment Law Project, an advocacy group.
And another 1 million workers will exhaust their 26 weeks in the first quarter of next year and will not be able to sign up for the federal extension.
If Congress chooses early next year to keep the extension in place, and makes the extension retroactive, many of the 2 million who fell off the rolls may be paid retroactively, said Rick McHugh, a NELP staff attorney.
Doctors' pay: Medicare physicians are facing a nearly 27% cut in their payments for treating Medicare patients because Congress has failed to pass the so-called doc fix to override that scheduled cut, as they usually do.
But here again there may be a few weeks' grace period for Congress to change its mind and reverse the cut. That's because claims are held for at least two weeks before they are paid.