Cobb County, home to Marietta and 766k Georgians, uses Georgia's distinctive 40% assessment ratio plus locally-set millage to compute property tax. Total millage combines county operations, school district, and city (where applicable) levies. Senior school exemptions are unusually generous in many GA counties — entirely exempting 62+ or 65+ residents from school millage, which is typically the largest portion of the bill.
How the bill is built
Georgia's calculation has three steps. Step 1: Assessed Value. Multiply fair market value by 40% — that's your AV (Georgia is one of the few states using a sub-100% assessment ratio for residential property). Step 2: Net AV. Subtract homestead exemption ($2,000 state minimum plus county add-ons; Fulton offers up to $30,000 for the county portion, Cobb/DeKalb $10,000, Forsyth $8,000). Step 3: Tax. Multiply Net AV by the total millage rate (county + school + city) and divide by 1,000. For the City of Marietta, total millage is approximately 30.02 mills.
2026 Cobb County rate breakdown (mills per $1,000 of assessed value (AV = 40% of FMV), Marietta district)
| Taxing entity | Rate |
|---|---|
| Cobb County operations | 8.4600 |
| Cobb County Fire | 2.8600 |
| Cobb County Schools | 18.7000 |
| Combined total | 30.0200 |
As of April 26, 2026 · From Cobb County Board of Tax Assessors.
Homestead, exemptions, and senior tax breaks for 2026
Georgia's homeowner tax relief works through layered homestead exemptions plus the unusually generous senior school exemptions in many counties. Most of these require a one-time application; once granted, they continue for as long as you qualify.
Standard Homestead Exemption
If Marietta is your primary residence on January 1 of the tax year, you qualify for at least the Georgia state minimum $2,000 homestead exemption. Cobb County typically offers an additional county-level homestead exemption that stacks on top. Cobb County offers a $10,000 county homestead exemption. File the homestead application by April 1 of the tax year with the Cobb County Board of Tax Assessors.
Senior School Exemption (the big one)
In Cobb County, residents 62+ or 65+ (varies by county) are entirely exempt from the school operations portion of the millage. Since school millage is approximately 18.70 mills out of the total, this saves $2,000-$3,500+ per year on a typical home. Most participating counties have no income limit. Apply with the Cobb County Board of Tax Assessors when you reach the qualifying age.
Disabled Veterans Exemption — $121,812 reduction
Veterans with a 100% service-connected disability rating (or rated as totally disabled under VA conditions) qualify for a $121,812 reduction in assessed value (2025; indexed annually). Since assessed value is 40% of fair market value, this protects approximately $304,530 of fair market value — for most Georgia homes this functions as a near-full exemption, particularly when stacked with the standard homestead. Surviving spouses and Gold Star spouses retain the exemption.
Appealing your assessment
Georgia's appeal process starts with the annual Notice of Current Assessment mailed in spring (timing varies by county; typically May-June). You have 45 days from the notice date to file an appeal with the Cobb County Board of Tax Assessors. The Board of Tax Assessors will review and either adjust or refer to the County Board of Equalization for a hearing. If still unresolved, the next step is Superior Court. Many GA counties also offer a non-binding arbitration option that can resolve appeals faster than the formal Equalization Board process.