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.