Here's yet another reason why you shouldn't do your own taxes: You could end up being grilled by the Senate Finance Committee.

That's what happened to Timothy Geithner, anyway.

You know the story by now: While working for the International Monetary Fund from 2001 to 2004, Barack Obama's choice for Treasury secretary failed to pay $34,000 in self-employment taxes. Geithner has since paid his debts, but he's been left in the embarrassing position of having to explain how a potential leader of the U.S. Treasury Department — the same outfit that oversees the IRS — could fail to pay his taxes.

Turns out he prepared the faulty returns himself.

“These were careless mistakes,” Geithner told the Senate panel. “They were avoidable mistakes, but they were unintentional. I should have been more careful.”

None of this is expected to derail Geithner's nomination. Still, if he had only hired a CPA — America's most trusted business professional — to do the returns for him, he could have avoided this mess entirely.

Lesson learned.