1. (a) The department shall calculate an annual index factor to be used for the rate to take effect each July 1 beginning in 2018 through July 1, 2027. The department shall determine the index factor before June 1 of each year using the method described in subsection (b).

2. (b) The annual gasoline tax index factor and special fuel index factor equals the following:

   1. (A) the STEP ONE result; and

   2. (B) the STEP TWO result.

      STEP FOUR: Divide the STEP THREE result by two (2).

   STEP ONE: Divide the annual CPI-U for the year preceding the determination year by the annual CPI-U for the year immediately preceding that year.

   STEP TWO: Divide the annual IPI for the year preceding the determination year by the annual IPI for the year immediately preceding that year.

   STEP THREE: Add:

3. (c) If the CPI-U or IPI for a preceding year is revised, corrected, or updated after May 31 of that year, the department shall use the CPI-U or IPI as published for the preceding year prior to revision.

As added by P.L.218-2017, SEC.37. Amended by P.L.185-2018, SEC.3; P.L.159-2021, SEC.31; P.L.201-2023, SEC.107.