For the tax years beginning on and after January 1, 1995, every corporation, whether a "subchapter S" corporation, as defined by the 1995 Internal Revenue Code, or not, foreign or domestic, that is doing business in Alabama, as a producer of coal mined in Alabama, shall be allowed a credit against the tax imposed by Section 40-18-2, in the amount of one dollar ($1) per ton of increased production of coal over the previous year's production of coal as set out herein below. Such tax credit shall be based on coal produced after January 1, 1995, provided the coal was mined in Alabama as certified by the producer of the coal. The amount of the total of credit in any one year shall be based on the number of tons of Alabama coal produced by the corporation in the year which exceeds the number of tons of Alabama coal produced by the corporation in calendar year 1994. In the event a corporation did not produce Alabama coal during calendar year 1994, such corporation must establish a base year by producing Alabama coal for 12 consecutive months. Thereafter, such corporation shall be eligible for the tax credit as specified hereinabove over the base year production.