You should be pretty certain about whether you're married or single. But what often confuses people is whether to choose head of household or single as their filing status, according to the IRS.

"Primarily, this is happening with divorced parents of minor children," said Dominique Molina, CPA and president of the American Institute of Certified Tax Coaches. "Either confusion as to who legally is entitled to claim the kids sets in, or one parent is illegally attempting to claim the children and the lucrative filing status that accompanies them."

Tax filing programs, like TurboTax or H&R Block, will help you figure out the right status to choose. But if you're filing on your own and are unsure which status is correct for your situation, you can use this tool on the IRS website.