(1) The Department shall establish rules and regulations and methods of apportionment and allocation so that only such part of net profits attributable to business activity conducted within the Zone directly by the taxpayer shall be entitled to a credit against net profits tax.

(2) A taxpayer, when filing its net profits tax return, shall first compute its net profits in conformity with Chapter 19-1500 or 19-2800 with no adjustments or subtractions for net profits attributable to business activity in the Zone, prior to calculating any credit under this Chapter.

(3) The credit against net profits tax allowed to a taxpayer in any tax year under this Chapter shall not exceed the net profits tax liability of the taxpayer for such tax year, and shall not carry forward to any other tax year.