For purposes of the regulations under section 6421, unless otherwise expressly indicated-
The term "qualified business use" does not include any use in a motorboat, other than a vessel used in the fisheries or whaling business. See paragraph (c) of this section for the definition of "highway vehicle." See paragraph (d) of this section for the definition of "highway."
Example. M Corporation, a logging company, files its income tax return on the basis of the calendar year. During 1982, the company used 20,000 gallons of gasoline in its logging business. Of this amount, 12,000 gallons were used as fuel in registered highway vehicles which were operated both on the public highways and on the company's private roads. Of the remaining 8,000 gallons, 6,000 were used in nonhighway vehicles, such as tractors and bulldozers, and 2,000 gallons were used in highway vehicles, such as heavy trucks which, at the time of use, were neither registered nor required to be registered under state law for highway use by reason of being operated entirely on the company's property. As the ultimate purchaser, M may take a credit on its income tax return for 1982 under this section in respect of the 6,000 gallons used in the nonhighway vehicles and the 2,000 gallons used in the unregistered highway vehicles. However, no credit may be allowed with respect to the 12,000 gallons used in the registered highway vehicles even though a portion of this gasoline was used in operating the vehicles on the company's own property.
26 C.F.R. §48.6421-4