Understanding how your Gwinnett County property tax bill is calculated is the first step toward knowing whether you are paying too much. Georgia property tax follows a consistent statewide formula, but the specific numbers — your home's assessed value, the millage rates set by each taxing authority, and the exemptions you qualify for — are unique to your property and your location within Gwinnett County.
Key Points
- •Georgia law sets the assessment ratio at 40% of fair market value (O.C.G.A. § 48-5-7).
- •One mill = $1 in tax per $1,000 of assessed value.
- •Your total bill combines county, school, and (if applicable) city millage rates.
- •Exemptions reduce your assessed value before the millage rate is applied.
- •The Tax Commissioner issues bills and collects payments.
The Three-Part Formula
Every Gwinnett County property tax bill is built from three numbers:
- Assessed value — 40% of your property's fair market value, as determined by the Gwinnett County Board of Assessors.
- Millage rate — the rate set by each taxing authority (the county, the school system, and your city, if applicable). One mill equals $1 of tax per $1,000 of assessed value.
- Exemptions — deductions that lower your assessed value before the millage rate is applied (homestead, senior, disabled veteran, and others).
The basic formula is:
Tax = (Assessed Value − Exemptions) × Millage Rate ÷ 1,000
Example (Illustrative)
If your home has a fair market value of $400,000, the assessed value (40%) is $160,000. If you have a homestead exemption that reduces your assessed value, and the combined millage rate from all taxing authorities is, say, 30 mills, your tax would be calculated on the net assessed value at $30 per $1,000.
Note: The millage rate and exemption amounts above are illustrative only. Always verify the current rates with the Gwinnett County Tax Commissioner.
Who Sets Each Part of the Rate
Your total property tax bill combines levies from multiple taxing authorities:
- Gwinnett County Board of Commissioners — sets the county government millage rate, which funds county operations, public safety, roads, and parks.
- Gwinnett County Public Schools (GCPS) — sets the school millage rate, which is typically the largest single component of a Gwinnett property tax bill.
- Your city or municipality — if you live inside an incorporated city (Lawrenceville, Duluth, Norcross, etc.), the city may levy its own millage rate for municipal services.
Residents in unincorporated Gwinnett County pay county and school taxes but typically not a separate city property tax.
Assessed Value vs. Market Value
Georgia law (O.C.G.A. § 48-5-7) requires that property be assessed at 40% of its fair market value. The Board of Assessors determines fair market value based on recent sales, property characteristics, and market analysis. Your assessment notice shows both the fair market value and the assessed (40%) value.
When Values Change
The Board of Assessors may reassess property values periodically. You will receive an assessment notice when your property's value changes. If you disagree with the new value, you have the right to appeal — see our Appeal Guide for the process.
Paying Your Bill
The Gwinnett County Tax Commissioner issues tax bills and collects payments. Bills are typically mailed in the fall. Payment methods and deadlines are posted on the Tax Commissioner's website.
Why It Matters to Gwinnett Residents
Gwinnett County has some of the highest property values in Georgia, which means even small millage-rate changes can translate to hundreds of dollars per year for the average homeowner. Understanding the formula lets you verify your bill and spot errors.
