Dec. 21 (Bloomberg) -- FedEx Corp., the second-largest U.S. package-shipping company, said it may have to pay $319 million in back taxes and penalties for misclassifying ground-delivery workers as contractors in 2002.

The U.S. Internal Revenue Service also is auditing the company's trucking unit for the years 2004 to 2006 to see whether workers were wrongly labeled as contractors rather than employees for tax purposes, FedEx said in a filing today. FedEx said it would have to pay interest on the 2002 bill.

``We believe that we have strong defenses to the IRS's tentative assessment and will vigorously defend our position, as we continue to believe that FedEx Ground's owner-operators are independent contractors,'' Memphis, Tennessee-based FedEx said.

FedEx is fighting the classification of contractors in courts around the U.S. This week, it was fined $190,000 by Massachusetts's attorney general for misclassifying 13 drivers as independent workers rather than full-time employees. The categorization determines taxes and benefits.

The FedEx Ground unit faces class-action lawsuits in federal court in Indiana, where contract drivers claim they are supervised and controlled as if they are employees. The company maintains the drivers work for themselves, not FedEx.

FedEx Ground is the company's second-biggest business by sales, behind its Express Air unit, with about 17 percent of 2007 revenue. There are about 14,000 FedEx ground contractors. The workers make $85,000 a year before taxes and business expenses, according to company spokesman Maury Lane.

FedEx rose 66 cents to $94.29 in New York Stock Exchange composite trading before the filing was made. The stock has dropped 13 percent this year.

The largest U.S. package-delivery company is Atlanta-based United Parcel Service Inc.

To contact the reporter on this story: Susanna Ray in Chicago at sray7@bloomberg.net.

Last Updated: December 21, 2007 20:12 EST