When the Board of Tax Assessors changes the value of property from the value in place for the preceding year or from the value that was returned by the taxpayer for the current year, a notice of change must be sent to the property owner. Upon receipt of this notice, the property owner desiring to appeal the change in 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