For a document just two pages long, the Form 1040 has plenty of pitfalls for taxpayers, errors that could needlessly boost your bill, require an amended return or even trigger an audit.
Americans spend a lot of time just filling out their tax forms each spring. Form 1040 filers toil over the two-page document for an average five hours, according to the IRS. (Overall tax-prep time for the Form 1040 is 16 hours, it reports, including record keeping and tax planning.)
A telling sign of its complexity: The Form 1040 has a 104-page instruction booklet detailing what you need to know to fill out those two pages. (Itemizing? Have a home business? Instructions for those schedules and others are separate.)
But it's not just the form. Most Americans would get an "F" when it comes to income tax basics, according to a new NerdWallet.com survey of 1,015 adults. The average respondent scored just 50 percent on questions including the tax implications of Roth IRAs, which volunteering expenses are deductible and the worst tax mistake (not filing).
Don't think you're safe if you're using tax preparation software, either. "The software is only as good as what you put in," said Tim Gagnon, an assistant academic specialist of accounting at Northeastern University's D'Amore-McKim School of Business. "It's a number cruncher." You might eliminate math errors, but enter the wrong information and you'll still get a wrong result.
That's where we come in. CNBC.com downloaded a copy of the Form 1040 from IRS.gov. Mouse over the pages below to see bull's-eye markers on lines that experts say are prone to error or miscalculation.