There's a good reason more than half of Americans pay someone else to prepare their taxes: It's easy to make mistakes.

Rushing to meet a high-pressure deadline like tax day -- which has been pushed to Monday, April 18, this year -- it can be even easier to slip up.

The growing popularity of tax preparation software and websites has managed to cut down on many mistakes. But whether you are filing an e-form or a traditional paper form, mistakes are still all-too common.

And those mistakes can end up costing you. You may not end up facing a larger tax bill or penalties if your misstep is small enough, it could end up netting you a smaller refund or at the very least delaying the arrival of your refund -- and nobody wants that.

Keep that in mind as you try to avoid these five common tax mistakes.

Tax Mistake No. 5: Mathematically Speaking >>