Seventeen of 19 paid tax preparers made mistakes in a small undercover study conducted by the Government Accountability Office that was released at a Senate hearing Tuesday.
And that study follows up a GAO survey concluding that people who did their own taxes had a 50 percent estimated error rate, in comparison to a 60 percent rate among paid preparers.
Yet only Oregon, Maryland, California, and New York regulate paid preparers.
In 2011, the Internal Revenue Service tried to implement a mandatory exam and education for all tax preparers who weren't certified public accountants, lawyers or enrolled agents.
But federal courts ruled that the IRS overstepped its statutory authority.
And at the heart of the issue is the need for tax simplification, says David Williams, chief tax officer at Intuit, maker of the TurboTax software.
"I could give you 20 different definitions of modified adjusted gross income," he says.