[WalterBright]

The tax code allows for losses from previous years to offset taxable income in the current year. It's a form of income averaging (which is allowed for personal income tax computation in some cases).

Income averaging is for companies that naturally have interspersed fat and lean years. For example, Boeing may invest enormous amounts of money in new aircraft development one year and make a bunch of money off of it the next year.

> The 379 profitable members of the Fortune 500 paid an effective federal tax rate of 11.3% last year

Since the tax rate is graduated, a technically "profitable" corporation who made only $10 in profit would pay 0% in income tax.

This is why such statistics, while pedantically correct, are usually nonsense because they deliberately omit such information.