1. (a) The department shall determine a new tax rate for the gasoline tax, the special fuel tax, and the motor carrier surcharge tax (before its repeal) to take effect July 1, 2017. The department shall determine the new rate before June 1, 2017. The new rate shall be determined by using annual factors and applying a method that is based on an annual factor being in place each year from the beginning of the period specified for each factor and that uses the resulting rounded rate for purposes of determining the following year rate change.

2. (b) The gasoline tax index factor to be used each year 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: Determine the year over year change in the CPI-U beginning in 2003 through 2016.

   STEP TWO: Determine the year over year change in the IPI beginning in 2003 through 2016.

   STEP THREE: Add for each year:

3. (c) The special fuel index factor and motor carrier surcharge tax index factor (before the repeal of the motor carrier surcharge tax) to be used each year 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: Determine the year over year change in the CPI-U beginning in 1989 through 2016.

   STEP TWO: Determine the year over year change in the IPI beginning in 1989 through 2016.

   STEP THREE: Add for each year:

As added by P.L.218-2017, SEC.37. Amended by P.L.185-2018, SEC.2.