3. Capital gains bite
The third big hit to wealthy taxpayers is an increase in the tax rate on qualified dividends and capital gains, from 15 percent to 20 percent for single taxpayers with AGI over $400,000. The rate remains 15 percent for taxpayers in lower tax brackets and 0 percent for taxpayers in the 10 percent and 15 percent income-tax brackets.
4. Limited deductions
After a three-year hiatus for wealthy taxpayers, the so-called Pease limitations—named after the Democratic congressman who introduced them in 1990—are back in force for the 2013 tax year. The rule limits the amount of itemized deductions that taxpayers with more than $250,000 in adjusted gross income ($300,000 for married couples) can claim on their tax returns. The limitation applies to things like mortgage interest, charitable contributions and state and local taxes but does not apply to items such as medical expenses, investment interest and casualty and theft losses.
Itemized deductions are reduced by 3 percent of the amount a taxpayer's AGI exceeds the thresholds, up to a maximum of 80 percent of total deductions. For example, a married couple with $400,000 in combined AGI will have their itemized deductions reduced by $3,000 (3 percent of $100,000). "The Pease limitations were not in effect between 2010 and 2012, but they made a comeback last year," said Stamper.
5. Lower medical-expense deductions
Another aspect of the Affordable Care Act will hit a wider range of taxpayers. Per ACA, the threshold for deducting medical expenses was raised from 7.5 percent of adjusted gross income to 10 percent. Taxpayers can now deduct only the cost of copays, insurance plan deductibles (both of which are generally rising), dental costs and other health-care expenses above 10 percent of their AGI. If you're over the age of 65, the 7.5 percent rate applies until 2017.
"The idea is to limit the deductions taken by higher-income taxpayers, but this could apply to almost anyone," said Iacobellis.
(Read more: How to keep the IRS auditors at bay)