"If your arithmetic is wrong, or your calculations are wrong, those are the types of things that create inconsistencies and often create exams that you don't need," said Steve Hurok, the tax director in the Woodbridge, N.J., office of the accounting firm BDO Seidman LLP.
The IRS doesn't have enough staff to do a high number of full-blown audits. It's much more likely you'll get a letter from the IRS questioning an item on a tax return -- and, accountants say, the more questions your return raises, the greater your odds of having to go through a more exhaustive examination.
As IRS employees go over a return and the information on it is entered into the agency's computers, the return is given a score called a discriminant function system, or DIF, score. The DIF score is reached by comparing the income, deduction and expense numbers on the return with other returns in a similar tax bracket or industry, and deviations from the norm can drive a DIF score higher and make a return more vulnerable to an audit.
"If things are very much out of whack after the return's been inputted, it could kick out," said Gregg Wind, a certified public accountant for Wind Bremer Hockenberg LLP in Los Angeles.
A high DIF score doesn't necessarily mean the big audit -- it may just mean that income, expenses or deductions, for example, are questioned. Still, you really don't want to call attention to your return.