"The way we choose tax forms for audit is based on a set of mathematical figures and norms," explained Sarah Wreford, an IRS spokeswoman in Detroit.

In other words, if $1,000 is the average amount of charitable gifts donated by a person making $30,000 a year and you donate $5,000, it might raise a red flag, Wreford said.

That's not to say you shouldn't be generous. You might just need to have your canceled checks, receipts and acknowledgement letters from the receiving organizations to prove your generosity, she said.

"Don't be afraid to take the deductions, just be prepared for a challenge," said Gregg Rozman, a certified public accountant and partner at BDO Seidman in Troy. "If it's legitimate, I would never advise a client not to take a deduction."

By the way, deductions for Girl Scout cookies, health spas and mileage to work are all a no-go at the IRS.

Tax experts say the following legitimate deductions get more scrutiny at the IRS and could require a paper trail to prove:

--Large charitable contributions. Again, include receipts, canceled checks and organization acknowledgement letters.

--Self-employed filers, otherwise known as Schedule C businesses. These get lots of IRS scrutiny because people tend to neglect claiming all their income. The trick: Claim all income.

--Home office deductions. If you try to deduct home office expenses, be prepared to prove the space is your primary place of work and is used exclusively for work. That means a community desk in the middle of the family room won't do.

--Large business expenses. Remember, you can't deduct expenses that already have been reimbursed. So be prepared to explain why your employer didn't pick up your expenses.

--Large business losses. "The IRS doesn't like losses," Rozman said. If you took a hit, be sure to have the paperwork to prove your investment and the loss, he said.