AMT patch

Expired already for 2012. Income exempt from the Alternative Minimum Tax in 2012 -- for which taxpayers will file returns next year -- falls to $33,750 for individuals and $45,000 for married couples. That's down from $50,600 and $78,750, respectively, if the exemption amounts had been adjusted for inflation.

As a result more than 30 million people will be hit by the so-called "wealth" tax, up from 4 million to date.

Payroll tax holiday

Expires. The Social Security tax rate reverts to 6.2 percent, up from 4.2 percent, on the first $110,100 in wages. Effectively, someone making $50,000 will pay another $1,000 in payroll taxes next year.

Unemployment benefits extension

The federal extension expires. That means workers who lose their jobs after July 1, 2012, will only receive up to 26 weeks in state unemployment benefits, down from as many as 99 weeks in state and federal benefits that had been available until recently.

By one estimate, more than 2 million claimants will lose their benefits by January.

Tax extenders

A host of smaller individual and business tax breaks will have expired. A bipartisan bill from the Senate Finance Committee proposes to extend many of them, but it has not passed the Senate or House yet.

Medicare doc fix

Expires. Medicare payment rates for physician services drops by 27 percent.

Other

Some budget experts count as part of the fiscal cliff the onset of a new Medicare surtax on high-income households under health reform.

But unlike the other fiscal cliff tax provisions, the new tax was not written into law as a wink-wink "temporary" provision. It is, however, included to reflect the magnitude of tax increases set to take effect simultaneously in 2013.

A 0.9 percent surtax will apply to wages on earned income over $200,000 ($250,000 if married). That's on top of the 1.45 percent Medicare currently owed on all wages. Those making between $200,000 and $500,000, for instance, will only pay about $633 extra while households making $1 million or more would pay another $11,242.

A 3.8 percent Medicare surtax will also apply for the first time to at least a portion of high-income households' investment income.