Taxpayers may challenge an assessment by the county board of tax assessors by appealing to the county board of equalization, an arbitrator or hearing officer within 45 days from the date of the assessment notice.  Taxpayers may appeal to the superior court of the county after a decision has been made by the county board of equalization.  Starting in 2011, every county must issue an assessment notice on every property.
Please see http://gaptp.com/ for more information on GA tax law reform.

Contacts for the State of GA:  Randy, Travis, Rick, James, Andy, Beau, Heather, Bobbi, Jay, Brandy, Hannah