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. May 10, 2017 19:26 Related articles Has the compressed natural gas tax rate increased? Has the undyed diesel tax rate increased? Who is entitled to the tare allowance for motor fuel taxes? Can an unlicensed exporter of petroleum products receive a refund for privilege taxes paid on the export of its products?