New wrinkles in the tax code areallowing some buyers of big SUVs towrite off up to the entire cost of the vehicleas a business expense. Section 179 ofthe code now lets you expense, ratherthan depreciate, up to $100,000 worth ofequipment used in your practice. Thatincludes all or part of the cost of an SUV,even if it's preowned, if you use it morethan half the time for business purposes.To qualify for the write-off, the vehiclehas to weigh more than 6000 pounds.The deduction is proportional to the percentageof time the vehicle is used inyour practice. If 75% of your use of theSUV is practice-related, for example,you can expense 75% of the total cost. Congress may be taking a secondlook at this tax break, so check with youraccountant before buying.