Transmission lines are subject to annual taxes per mile [1.61 kilometers] or fraction of a mile based on their nominal operating voltages on January first of each year, as follows:

1.    For transmission lines that operate at a nominal operating voltage of less than fifty kilovolts, a tax of fifty dollars.

2.    For transmission lines that operate at a nominal operating voltage of fifty kilovolts or more, but less than one hundred kilovolts, a tax of one hundred dollars.

3.    For transmission lines that operate at a nominal operating voltage of one hundred kilovolts or more, but less than two hundred kilovolts, a tax of two hundred dollars.

4.    For transmission lines that operate at a nominal operating voltage of two hundred kilovolts or more, but less than three hundred kilovolts, a tax of four hundred dollars.

5.    For transmission lines that operate at a nominal operating voltage of three hundred kilovolts or more, a tax of six hundred dollars.

6.    A transmission line initially placed in service after January 1, 2009, and before December 31, 2013, is exempt from transmission line taxes under this section for the first taxable year after the line is initially placed in service, and transmission line taxes under this section must be reduced by:

a.    Seventy-five percent for the second taxable year of operation of the transmission line.

b.    Fifty percent for the third taxable year of operation of the transmission line.

c.    Twenty-five percent for the fourth taxable year of operation of the transmission line.

d.    After the fourth taxable year of operation, such transmission lines are subject to the standard transmission line taxes under this section.

7.    A transmission line of two hundred thirty kilovolts or larger initially placed in service after January 1, 2009, is subject to a tax at the rate of three hundred dollars per mile [1.61 kilometers] or fraction of a mile. A transmission line subject to tax under this subsection is exempt for the first taxable year after the line is initially placed in service, and transmission line taxes under this subsection must be reduced by:

a.    Seventy-five percent for the second taxable year of operation of the transmission line.

b.    Fifty percent for the third taxable year of operation of the transmission line.

c.    Twenty-five percent for the fourth taxable year of operation of the transmission line.

d.    After the fourth taxable year of taxable operation, such transmission lines are subject to the standard transmission line taxes under this subsection.

8.    For purposes of this section, “initially placed in service” includes both new construction and substantial expansion of the carrying capacity of a pre-existing line, and “substantial expansion” means an increase in carrying capacity of fifty percent or more.