An Internal Revenue Service spokeswoman says the worst thing last-minute tax filers can do is panic.

Karen Connelly says up to 25 percent of taxpayers wait until the last week to file their return and the percentage of mistakes on those returns tends to be higher than the overall average for the tax season. She says a surprising number of the mistakes are such basic things as forgetting to sign a return or entering a wrong Social Security number.

Connelly also reminds taxpayers expecting a refund through direct deposit to double check their bank account and routing numbers. Connelly says it's important to set aside enough time to correctly file your return, and reminds people they can always file for an extension if that isn't possible.

People can file for extensions using IRS form 4868, which can be filed free of charge from the IRS website. The extension is for six months, but Connelly says to avoid penalties if you owe money you should pay at least 90 percent of your estimated tax debt by April 15th.