(a) Except as provided in subsection (b) of this Code section, not later than April 11 in each year the tax receiver or tax commissioner of each county shall present the tax returns of the county for the current year to the county board of tax assessors.

(b) In all counties having a population of not less than 81,300 nor more than 89,000 according to the United States decennial census of 1990 or any future such census, the tax receiver or tax commissioner of each such county shall present the tax returns of the county for the current year to the county board of tax assessors not later than March 11 of that year.