NEW YORK (CNNMoney.com) -- April 30 is the day that Americans can stop working to pay the taxman and start working for themselves, according to the Tax Foundation's annual estimate dubbed "Tax freedom day."

Tax freedom day is theoretical because it assumes we've been working 7 days a week since the start of the year, and that we don't spend anything we make. The 120 days from Jan. 1 through April 30 represents the time it will take the nation as a whole to earn enough to pay off all of the taxes that will be levied against us this year.

Breaking that 120 days down, the Tax Foundation estimates it will take:

43 days of work to pay off federal, state and local income taxes

30 days to pay off payroll taxes (for Social Security and Medicare)

16 days to pay off sales and excise taxes

14 days to pay off corporate income taxes (This assumes that a tax on a business is passed on to its customers, employees and shareholders in terms of higher prices, lower paychecks and less shareholder value.)

12 days to pay off property taxes

4 days to pay off other taxes (e.g., customs duties)

1 day to pay off estate and gift taxes

Tax freedom day may not literally provide Americans with any relief. But as a point of comparison it is a way to measure changes in the total tax burden of the nation from one year to the next.

This year's tax freedom day comes four days later than it did in 2006, representing the fourth increase in four years. It's taking Americans longer to pay their tax bill, according to the Tax Foundation, primarily because overall income has increased, property taxes are up and the annual cap on wages subject to the Social Security and Medicare tax has also increased

The total effective tax rate for the nation - a measure of all taxes as a percentage of all income - is 32.7 percent this year, up slightly from 2006.

On a state-by-state basis, tax freedom day comes much sooner in some places such as Oklahoma -- where residents will have earned enough to pay their taxes by April 12 -- than in states with high taxes or high per-capita income, such as Connecticut, where residents have to work through May 20 to satisfy the total tax burden there.

See how your state ranks

Watching the clock - literally

The Tax Foundation also compares the time Americans work to pay taxes with the time we work to pay for life's other expenses.

Based on an 8-hour workday, the research group estimates that Americans as a whole work: