The Internal Revenue Code imposes an excise tax on fuel, such as diesel fuel, that is used in a diesel-powered highway vehicle. Treas. Reg. 48.4041-7, which was finalized in 1986, provides that tax applies to all liquid fuel sold for use or used to propel a diesel-powered vehicle or in a motor used to propel a motor vehicle, motorboat or aircraft, even though the motor is also used for a purpose other than propulsion, such as operating special equipment by means of a power-take off (PTO) or similar device. The regulations allow a taxpayer to treat taxable fuel used in an auxiliary power unit (APU) as nontaxable. However, some industries have shifted away from APUs in favor of PTOs to power special equipment installed on trucks.

In 2019, the IRS and the Treasury Department issued Notice 2019-10, which requested comments on how the provisions of Treas. Reg. 48.4041-7 could be revised to expand the exemption to fuel used in the propulsion motor of a vehicle to power auxiliary equipment unrelated to the propulsion of the vehicle by means of a PTO.