For tax years beginning before January 1, 2020, a one-time income tax credit is available for 45% of the incremental cost of purchasing a new original equipment manufacturer AFV, excluding electric vehicles, or converting a vehicle to operate on an alternative fuel. The state also provides a tax credit in the amount of 10% of the total vehicle cost, up to $1,500, if the incremental cost of a new AFV cannot be determined or when an AFV is resold, as long as a tax credit has not been previously taken on the vehicle. Equipment used for conversions must be new; must not have been previously used to modify or retrofit any vehicle; must meet applicable federal and state safety standards; and must be installed by a state certified alternative fuels equipment technician. The alternative fuels eligible for the credit are compressed natural gas, liquefied natural gas, hydrogen, and liquefied petroleum gas (propane). Tax credits may be carried forward for up to five years.