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

(2) A qualified business, when filing its business privilege tax return, shall first compute its receipts and net income in conformity with Chapter 19-2600 with no adjustments or subtractions for receipts or net income attributable to business activity in the Zone, prior to calculating any credit under this Chapter.

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