SUV and truck buyers who use heavyweightvehicles for business got a big fattax break from the 2003 tax law. Underthe law, the rules on expensing businessequipment allowed a buyer of any vehiclethat weighs more than 6000 pounds fullyloaded to write off the entire cost, up to$100,000. The measure was aimed athelping those who use big pickups andtrucks on the job, like farmers and contractors.But the law also included somesnazzy, not necessarily utilitarian sportutility vehicle (SUV) models like theCadillac Escalade and the monsterHummer. Now Congress is backing offthe big deduction. The recently signed taxbill limits the write-off for big vehicles to$25,000. Big-vehicle buyers may stillbe able to combine the $25,000 write-offwith the law's bonus depreciation andstandard depreciation to deduct most ofthe cost of an SUV.