The "fiscal cliff" deal will help millions of Americans avoid paying the dreaded alternative minimum tax—while making it harder for many upper-middle class taxpayers to escape it, analysts say.
The reason is that the minimum income levels subject to the AMT are going up, but wealthier Americans won't be able to take as many deductions as before. (Read more: Your Taxes Going Up)
The fiscal cliff deal does two things: it permanently adjusts AMT income exemption levels to inflation while giving lower-income taxpayers bigger exemptions and new credits to take them out of the AMT.
For instance, the AMT exemption for 2012 has been raised to $50,600 for singles, up from $33,750, and $78,750 for married couples, up from $45,000. That will keep millions of lower-income Americans from paying the tax.
"The big winners in this are those in the $45,000 to $105,000 income range," said Bob Phillips, CFP, Managing Principal at Spectrum Management Group. "They can now use credits like the child credit, dependent care credit and the life time education credit in their calculations to lower their income and keep them out of AMT tax brackets."
The losers are higher-income Americans, who will likely continue to be hit by the AMT because they won't get the same tax breaks from the deal, said Leon C. LaBrecque, senior financial advisor and CEO at LJPR, LLC.
Among the tax breaks lost for higher incomes are itemized deductions for mortgage interest. Those will now be capped for individuals making more than $250,000 and couples making more than $300,000.
"For those in the $450,000 income level they're getting hit the hardest by the AMT because they are not part of those being able to use any of those deductions that lower income levels are now getting," said LaBrecque.
Created in 1969, the AMT is basically a parallel tax that has excluded certain deductions—like state and local income taxes that help lower income levels and taxes—for people making a certain amount of money each year. That means taxpayers in AMT brackets have had to figure out which tax is more, the AMT or regular taxes — and then pay the higher amount.
Up until now, the AMT has never been indexed to inflation, so every year more Americans were caught in its brackets as their salaries inched up. Congress has traditionally created patches in years past to keep the AMT from hitting more taxpayers.
If no fiscal cliff deal had been reached, an estimated 29 million more Americans—in addition to the current 4 million—could have been subject to the AMT in their 2012 returns. (Read more: Fiscal Cliff Key Points)
This permanent indexing will help settle the question for many of 'Will I or won't I pay the AMT,' say analysts.
"The inflation index has been sorely missing from the AMT since it's beginning," said Howard Kaplan, a CPA/PFS in Englewood, N.J. "Millions of people at the lower incomes who might be paying because of that won't be now."
AMT rates currently range from 26 percent for singles to 28 percent for married. Those rates are currently the same in the fiscal cliff deal.
More than half of AMT revenue in 2010 came from households with incomes over $200,000, according to the Center on Budget and Policy Priorities. But more upper-middle-income households have been hit than high-end incomes.
While Congressional Republicans have called for an end to the AMT—and President Obama proposed the so called Buffett tax to replace it—the problem for the country and deficit is the revenue it brings in. (Read more: How Cliff Deal Helps Real Estate )
The original AMT collected just $122 million — about $700 million in today's dollars — which was just over one-tenth of one percent of all individual income tax revenue. Fast forward to the last tax year of record, 2010, and some $102 billion was collected.
"We need the money and so it's easy to say get rid of it, but what would replace it?" said LaBrecque. "I'm not saying it's great, but this deal is the best we can hope for when it comes to the AMT."
And for one analyst, the new AMT patch and all that comes with it allows for some permanency that's been lacking.
"It allows us as well as taxpayers to know what's going on instead of waiting for Congress to do a fix each year," said Bob Phillips, CFP, Managing Principal at Spectrum Management Group. "That's worth something."
--by CNBC.com senior editor Mark Koba