(a) As used in this Code section, the term "business enterprise" means any business or the headquarters of any such business which is engaged in manufacturing, warehousing and distribution, processing, telecommunications, tourism, and research and development industries. Such term shall not include retail businesses.

(b) A tax credit is allowed a business enterprise having a Georgia net taxable income in the current taxable year which is 20 percent or more above that of the preceding taxable year, if such business enterprise's Georgia net taxable income in each of the two taxable years preceding the current taxable year also was 20 percent or more above each respective preceding taxable year.

(c) The tax credit provided in subsection (b) of this Code section shall be the excess over 20 percent of the percentage growth in the business enterprise's Georgia net taxable income in the current taxable year, provided that the tax credit shall not exceed 50 percent of the business enterprise's Georgia net income tax liability after all other credits have been applied for the current taxable year and shall not be allowed if the total Georgia income tax liability before application of the credit exceeds $1.5 million.

(d) The tax credit provided in subsection (b) of this Code section may not be carried backward or forward.