As a reminder, homeowners have 45 days after receiving their Annual Notice of Assessment to file a written appeal. (The notice includes the deadline date.)
In case you were not aware, the county does make periodic onsite visits to update their property record from which to more accurately determine fair market values and/or make other determinations. More information can be found at www.CobbAssessor.org.
Don’t rely on the county’s opinion of value when preparing to sell. A Realtor and/or appraisal are a better resource for determining the potential sale price.