from the WSJ:
Alternative minimum tax
• Status: The "patch" to narrow this tax's reach for the 2010 tax year hasn't been passed yet by Congress. Thus the exemption for married joint filers is currently $45,000, as opposed to nearly $71,000 last year. If the patch doesn't get done, 32 million taxpayers will owe AMT in 2010 versus 5 million last year.
Clint Myers, an investment actuary in Georgetown, S.C., figures it would raise his tax bill 10%—more than the expiration of the 2001 tax cuts would.
• What's ahead: Congressional tax staffers say they think the patch will get done when Congress addresses income-tax issues.
• What to do: People who owe estimated taxes are supposed to be paying at higher "nonpatch" rates until Congress fixes the problem. You can avoid paying at these higher rates or risking penalties by using an IRS "safe harbor," such as paying 110% of last year's taxes.
• Also: if tax rates go up next year, it becomes harder to fall into the AMT. Thus deductions may become more valuable, says Douglas Stives, an accounting professor at Monmouth University in New Jersey.