A sole proprietor that owns and runs an 18 wheeler is probably using diesel fuel pumped from a truck stop. Federal excise taxes are imposed on diesel as well as other fuels. Claiming a Fuel Tax Credit on diesel fuel is only available for vehicles used in farming, off-highway business use, commercial fishing boats, aviation, trains, and other government and nonprofit organizations. Publication 510 describes Excise Taxes as well as the instructions for Form 4136 Credit for Federal Tax Paid on Fuels can be downloaded from the IRS website at www.irs.gov.