Congress managed to extend the payroll tax cuts for workers for two more months, but it allowed other tax breaks that are important to business to expire Jan. 1.

Some of these tax breaks may be reinstated later in the year and then applied retroactively - that's been a common occurrence for the research-and-development tax credit. Congress also will likely find a way to protect middle-income taxpayers from the alternative minimum tax.

The outlook isn't clear, however, for tax breaks encouraging businesses to invest in new equipment. Last year, small businesses could expense up to $500,000 in capital expenditures instead of depreciating them over time. This Section 179 expensing limit fell to $125,000 (subject to an adjustment for inflation) this year and will drop to $25,000 in 2013, unless Congress takes action.

For investments in new equipment that went beyond the Section 179 limit, businesses - in most cases - could write off all the costs last year. This 100 percent bonus depreciation dropped to 50 percent this year, however.