Has the undyed diesel tax rate increased? Yes. Beginning July 1, 2017, the undyed diesel tax rate is increased to 21 cents. See important notice 17-08 for rate increases for subsequent years. December 11, 2017 15:45 Related articles Has the undyed diesel tax rate increased? Has the gas tax rate increased? Who is entitled to the tare allowance for motor fuel taxes? Has the compressed natural gas tax rate increased? I am a wholesaler with gasoline and/or undyed diesel fuel in stock that I previously purchased for sale. Do I need to pay a floorstock tax?