Every year the Board of Tax Assessors send out notices of value to each property owner. Upon receipt of this notice, the property owner desiring to appeal the value must do so within 45 days of the date of the notice. The appeal is filed with the Board of Tax Assessors, which reviews the appeal filed and informs the taxpayer of its decision. If the Board of Tax Assessors makes no changes, the appeal is automatically forwarded to the County Board of Equalization. A hearing is scheduled, conducted and the Board of Equalization renders its decision. If the taxpayer is still dissatisfied with the decision, an appeal to Superior Court may be made.
https://dor.georgia.gov/documents/pt-311a-appeal-assessment-form