If you think the only thing Uncle Sam is squeezing from most Americans at income tax time is money, think again. He also got a huge slice of our time.

As of April 15, America's 100 million taxpayers had spent at least 2 billion hours preparing for and making out their state and federal tax returns, according to University of Michigan economist Joel Slemrod.Slemrod, director of the School of Business Administration's Office of Tax Policy Research, figures the average cost for complying with the tax laws for time spent and professional tax assistance fees at $275 per household, or $27 billion nationwide.

Slemrod has found that it takes a taxpayer an average of 21.7 hours per year to complete his taxes. Two-thirds of that time is devoted to record keeping, one-tenth to research and one-fifth to filling in the blanks on the form.

The self-employed, Slemrod says, average an additional 35 hours and an extra $69 getting their forms in order because their records are more complicated.