And even if a mistake, either on your computer or paper forms, doesn't cost you cash, it could delay the receipt of any refund you're expecting.
Tax changes also complicate the annual tax-filing exercise. For the 2013 tax year, some higher income taxpayers (and their tax preparers) will have to decipher the 3.8 percent tax on investment income.
Special tax scenarios aside, there are still plenty of ways to mess up a 1040 form. Here are 10 common mistakes that show up every tax season. As you review your tax return for filing on this Oct. 15 deadline day, make sure you haven't made any of them.
1. Math miscalculations
The most common error on tax returns, year after year, is bad math. Mistakes in arithmetic or in transferring figures from one schedule to another will get you an immediate correction notice. Math mistakes also can reduce your tax refund or result in you owing more tax than you thought.
Using a tax software program to file your return can help reduce math errors. The built-in calculators do the work for you, adding, subtracting and inserting numbers on additional forms as needed. But you still have to make sure your initial numbers are correct. Entering $3,500 when the real figure is $5,300 makes a lot of tax difference. Getting the numbers right is crucial because you can be sure the IRS will be double-checking numerical entries against its copies of your tax statements (W-2, 1099s and the like).
When IRS examiners find a discrepancy, they'll definitely let you know and, in many cases, will correct your mistake and refigure your taxes for you. Don't give them the chance. Make sure your math entries are right.
2. Computation errors
These are cousins to the standard math mistakes. In these computation cases, taxpayers or their tax pros make mistakes in figuring such tax-return entries as taxable income, withholding and estimated tax payments.