Anchor Lead: Taxes can be complicated, which means it's easy to make mistakes ... mistakes that could have gotten you a bigger refund ... or could get you in hot water with the IRS. But just because a mistake is made doesn't mean it can't get corrected. Here's money reporter Stacy Johnson with some quick advice on fixing problems now before they become bigger problems later.

Voiceover 1: "In my 34 years I have probably seen every error that could ever be made on a tax return made. The main ones is that people forget they have W-2s and they forget 1099Rs."

Voiceover 2: Combine a complex and convoluted income tax code with regular human beings, and you're pretty much asking for trouble.

Voiceover 3: (IRS video) Maybe that's why the IRS has made fixing problems pretty much trouble-free. You can easily fix any mistake you make -- even after you've already sent off your return.

Voiceover 4: All you need is this: It's a 1040X.

SOT: "It has two columns on it ... it has one for the previous tax return and one for the new one. You just determine the new tax, send it to the IRS and if you owe them money you send them money and if they owe you money they'll send you a refund. It's just that simple."

Voiceover 5: So basically a 1040X is a do-over. You're telling the IRS what you originally reported, what your corrected numbers are and what went wrong.

Voiceover 6: When do you file a 1040X? One obvious situation is when you can get more money back. But even if you have to pay, better you catch the error than Uncle Sam.

Standup There's a time limit on fixing mistakes with a 1040X: You can only use it to go back three tax years. So if you think you made a mistake on a prior year return, don't sweat it ... fix it. For Bankrate.com, I'm Kristin Arnold.