In passing a tax bill to forestall the "fiscal cliff" -- the overnight rise of a wide array of taxes combined with deep spending cuts -- lawmakers agreed to permanently index the Alternative Minimum Tax for inflation.

The AMT, as it is commonly known, it is a separate income tax calculation that was intended to ensure that wealthy people did not use loopholes to avoid paying taxes. Once a taxpayer reaches a certain income level, they need to pay the amount calculated under the AMT even if the deductions and exemptions available under in the regular tax code would otherwise allow them to pay less in tax.

But the AMT, unlike the standard tax code, was not indexed for inflation. So, every year, more and more Americans hit the threshold and found themselves owing higher taxes. As a result, the AMT was increasingly becoming a burden on the middle class, or at least the upper-middle class, rather than the rich.

In recent years, lawmakers have "patched" the AMT in a way that kept it from hitting many non-wealthy taxpayers. But this produced regular headaches for lawmakers.

The fiscal cliff bill, passed by the House and Senate on Jan. 1, 2013, ends the need to regularly patch the AMT by permanently indexing the AMT for inflation. We rate this a Promise Kept.