A new top tax rate, higher Medicare taxes and the phaseout of deductions and exemptions could mean higher tax bills for wealthier Americans this year. Legally wed same-sex couples, meanwhile, may find the true meaning of the marriage penalty.
All taxpayers will have a harder time taking medical deductions.
In other changes for the 2013 tax year, the alternative minimum tax has been patched — permanently — to prevent more middle-income people from being drawn in, and there's a simpler way to compute the home office deduction.
Tax rate tables and the standard deduction have been adjusted for inflation, as has the maximum contribution to retirement accounts, including 401(k) plans and individual retirement accounts, or IRAs.
The provisions were set by Congress last January as part of legislation to avert the so-called fiscal cliff of tax increases and spending cuts. "We finally got some certainty for this year," said Greg Rosica, a contributing author to Ernst & Young's "EY Tax Guide 2014."
Nevertheless, the filing season is being delayed because of the two-week partial government shutdown last October. The Internal Revenue Service says it needs the extra time to ensure that systems are in place and working. People will be able to start filing returns Jan. 31, a week and a half later than the original Jan. 21 date.
"People who are used to filing early in order to get a quick refund are just going to have to wait," said Barbara Weltman, a contributing editor to the tax guide "J.K. Lasser's Your Income Tax 2014."
No change in the April 15 deadline, however. That's set by law and will remain in place, the IRS says.
-- Higher-income taxpayers
The tax legislation passed at the start of 2013 permanently extended the George W. Bush-era tax cuts for most people but also added a top marginal tax rate of 39.6 percent for those at higher incomes — $400,000 for single filers, $450,000 for married couples filing jointly and $425,000 for heads of household.
On top of that, higher-income taxpayers could see their itemized deductions and personal exemptions phased out and pay higher capital gains taxes — 20 percent for some taxpayers. And there are new taxes for them to help pay for the new health care law.
There are different income thresholds for each of these new taxes.
An additional 0.9 percent Medicare tax, for example, kicks in on earnings over $250,000 for married couples filing jointly and $200,000 for singles and heads of household. Same for an extra 3.8 percent tax on investment income.
But the phaseout of personal exemptions and deductions doesn't begin until $300,000 for married couples filing jointly and $250,000 for singles.
Taxpayers who didn't plan could find themselves with big tax bills come April 15 — and perhaps penalties for under-withholding.
"It's a snowball effect," said Dave Du Val, TaxAudit.com's vice president of customer advocacy.
"The complexities of the tax code are only affecting those of us trying to read it," National Taxpayer Advocate Nina Olson said in an interview. Tax software makes a lot of those complexities invisible to most people.
As a result, taxpayers might not realize they're being helped by a wide array of deductions and credits. "They have no idea of the benefits they are getting through the tax code," she said.