From the CCH Tax Briefing:
The American Taxpayer Relief Act extends through 2013 enhanced Code Sec. 179 small business expensing. The Code Sec. 179 dollar limit for tax years 2012 and 2013 is $500,000 with a $2 million investment limit. The rule allowing off-the-shelf computer software is also extended.
IMPACT: Without the American Taxpayer Relief Act, the Code Sec. 179 dollar limit for tax years beginning in 2012 would have been $125,000 (subject to inflation adjustment) with a $500,000 investment limit (again, subject to inflation adjustment). In tax years after 2012, the dollar limit would have reverted to $25,000 with a $200,000 investment limit. This significant decrease in the value of the incentive has now been postponed to tax year after 2013.