An excise tax is hereby levied upon every person who severs gas in the state for sale, transport, profit, or commercial use. Except as otherwise provided in this part, the tax shall be levied on the basis of the entire production of gas in this state, including any royalty interest. Such tax shall accrue at the time the gas is severed and shall be a lien on production regardless of the place of sale, to whom sold, or by whom used and regardless of the fact that delivery of the gas may be made outside the state.(1) The amount of tax shall be determined by the volume, in mcf, of gas produced and sold or used by a producer during the month, measured at the point where the gas is identifiable as to kind and quality and is capable of being transported for further use or processing, subject to the gas tax rate established in this section. For each fiscal year, the gas tax rate shall be the gas base rate times the gas base rate adjustment for the fiscal year, as calculated by the department under subsection (3).
(2) The gas base rate shall be $0.171 per mcf.
(3)(a) On or before May 15, 1987, and annually thereafter, the department shall determine the gas base rate adjustment and the resulting gas tax rate for the fiscal year beginning on the following July 1.
(b) The gas base rate adjustment for the fiscal year is a fraction, the numerator of which is the annual average of the gas fuels producer price index, Commodity Code 053, as calculated and published by the United States Department of Labor, Bureau of Labor Statistics, for the previous calendar year, and the denominator of which is 1109.0.
(c) The department shall provide the gas base rate adjustment and the gas tax rate for the fiscal year, as determined under this subsection, to affected producers by written notice mailed on or before June 1.
(d) If the index used to determine the gas base rate adjustment is substantially revised, or if the base year for the index is changed, the department shall make appropriate adjustment to the method used to determine the gas base rate adjustment to ensure a result which is reasonably consistent with the result which would have been obtained had the index not been revised or the base year changed.
(e) If the gas fuels producer price index is discontinued, a comparable index shall be adopted by the department by rule.
(4) Gas production shall be measured or determined by meter readings from meters showing 100 percent of the full volume of gas produced and shall be expressed in mcf.
(5) The tax imposed under this section shall be administered, collected, and enforced by the department.
(6) This section applies only to native gas as defined in s. 377.19. 
