As CBS News correspondent Bob Orr reports, once the deadline's been met, how does the money end up getting spent?
In total, the average tax bill this year tops $13,000, and most taxpayers have no idea what the government is doing with their cash.
"They might know in some broad sense that we spend hundreds of billions of dollars on this or that, but they have no idea really what their money is going for," says taxpayer advocate Jim Kessler.
Kessler's non-profit group has prepared a "receipt" - an itemized breakout of government spending.
What's Uncle Sam is spending the most taxpayer money on? Defense.
The average American household is paying $2,761 for defense in 2007, or put another way, enough to cover 12 car payments for a new Honda Accord.
Social Security is nearly as expensive: $2,663. That's about enough to heat and cool a home for a year.
Read the report "What You Paid For."
The average household is paying $19 for the office that tracks hurricanes, about the cost of a fancy umbrella. And just over $12 for National Parks, the cost of one bleacher seat at D.C.'s new Nationals Park.
Some items seem like relative bargains: $313 for education; $99 for farmers; just $62 for all federal law enforcement.
But another big ticket item is interest on the National Debt. For this, the average taxpayer is forking out more than $1,000 this year.
"That's like taking $1,000 and lighting a match to it," Kessler said.
Some government spending is paid for with pocket change. The Consumer Product Safety Commission, which monitors toy safety, costs just 29 cents a year. And the White House? Even less. It costs just 18 cents.
But nothing about government is free.
The tax man himself at the IRS costs the average American family $49 a year - about the same price of the software you'll need for next year's taxes.