Midnight tonight is the deadline to file income tax returns, but it is not too late to file the returns online or request an extension over the phone.

Four-month extension forms are available at the Internal Revenue Service website, but tax payments are still due today. The IRS assesses late-payment penalties and interest if the total tax due is not paid by the deadline. The state may also assess penalties and interest.

IRS employee Sharon Hansen said students usually do not make many mistakes on their tax returns, but one mistake she often sees is both students and their parents claiming a student as a dependent. Only one person in the student’s family can claim the student as a dependent, indicated on either the student’s form or the parents’ form.

“Not knowing whether your parents claimed you as a dependent is the most common mistake,” Hansen said. “Just check with your parents.”

John Hiddleson, tax specialist for the IRS’s Education and Communication Department, said students and parents both claiming exemptions is “absolutely the biggest” mistake students commonly make.

“Whoever files the return first, the other has to amend the return,” Hiddleson said. “The second biggest error is if the student is claimed as a dependent, missing the standard deduction.”

Students can only take tax breaks on the form where the student is claimed as a dependent, and deductions only apply to tuition and fees, not including room, board and books. If the parents claim the student as a dependent, they get the tax breaks. The standard deduction for a single college-aged student is $4,700.

Hiddleson said that surprisingly enough, the other most common mistakes he sees are unsigned returns and names not printed exactly as shown on the Social Security card.

According to the IRS, two of the five most common errors on tax returns include simple mistakes like incorrect or missing Social Security numbers and mistakes in math calculations. Another common mistake is failure to include W2 forms. If a student cannot find their W2 form, they should contact their employer and still submit their tax returns using a special form available at the local library or post office, determining the year’s income through pay stubs.

Out-of-state students who work in Wisconsin might also need to file tax returns both in their home state and in Wisconsin. To find out whether to file a tax return in two states, contact your local state tax office, available at the IRS website.

Hiddleson said an extension of time to file taxes does not extend the time to pay the tax.

“The payment is still due if you end up owing more and need more time to file,” Hiddleson said. “The clock is ticking.”

To request an extension, call 1-888-796-1074. Additional tax information is available at