Tuesday is the final day businesses must send out W2 forms by mail, which means the tax season is upon us.
Also upon us are the stacks of paperwork, hundreds of numbers and tons of information to keep up with, opening the door for mistakes.
"You know mistakes happen," said tax preparer Samantha Slapnik. "People are human."
But Slapnik says there are common errors you can avoid.
"If you are married you have two options. You are married filing separately or married filing jointly. There's a very common misconception you can file head of household if you are married. You really can't," said Slapnik. "Or file single because it works out better for you. You can't really change the rules. It's very specific in the tax code."
Other common mistakes include claiming dependents that you don't support or claiming single when you are separated and lived with your spouse at any time during the past six months.
Filers also common make errors on social security numbers, names and birth dates. That slows down the process.
The 2011 tax code includes hundreds of changes from last year's.
Slapnik says the do-it-yourself tax software is good for about 90 percent of Americans. The other 10 percent, those dealing with more paperwork, have a greater chance for mistakes, said Slapnik.
"If you don't know what questions to ask or what credits to look for or deductions to look for, you're either missing out or you're not reporting correctly and that is going to lead up to some fun IRS letters in the future."
Slapnik said it takes about two years for the IRS to notice mistakes, and many people throw away or lose their information during that time.
The deadline to send out this year's tax returns and extensions is April 17th.