(a) Except as provided in subsections (b) and (c) of this Code section, the minimum capital stock of a de novo bank or trust company shall be $3 million.

(b) A de novo bank or trust company whose main office is located in a county with a population of less than 200,000, according to the last official United States census, shall have a minimum capital stock of $2 million.

(c) A bank or trust company existing on July 1, 1989, with a capital stock of less than that required by subsections (a) and (b) of this Code section shall not be required to increase its capital stock above the amount outstanding on July 1, 1989, except as otherwise provided by law.