Why Did My Cobb County Property Tax Bill Go Up in 2026?

You open the property-tax bill, look at the total and ask the question homeowners across Cobb County are asking right now:

“Why did this go up?”

It is a reasonable question, especially when you have heard that a millage rate stayed the same or that a homestead exemption protects homeowners from rising values.

The answer is usually not one dramatic change. A property-tax bill is the result of several moving parts: the property’s fair market value, its assessed value, the exemptions attached to it, the millage rates adopted by each taxing authority and, in some locations, a separate city bill.

Understanding those pieces can help you spot an error, budget intelligently and protect the value you have built.

First, understand the basic calculation

Georgia generally assesses real property at 40% of fair market value. If a home is assigned a fair market value of $500,000, its gross assessed value would be $200,000 before applicable exemptions.

A mill is $1 of tax for every $1,000 of taxable assessed value. The simplified formula is:

Fair market value × 40% − applicable exemptions × millage rate = estimated tax

The actual calculation can involve several tax districts and exemption rules, so this formula is best used as a framework rather than a substitute for the official bill. The Georgia Department of Revenue provides the statewide explanation and examples. Georgia Department of Revenue

A flat millage rate can still produce a higher bill

This is the part that causes the most confusion.

The millage rate is only one side of the equation. If the taxable assessed value rises, the tax can rise even when the rate stays unchanged.

For example, the City of Marietta announced a proposed 2026 rate of 4.692 mills, equal to the previous year’s rate. The city also stated that the unchanged rate would generate more property-tax revenue than the prior year. That can happen when the tax digest grows through new construction, ownership changes or higher taxable values. City of Marietta

In other words, “no rate increase” and “no tax increase” are not the same statement.

Your fair market value may have changed

The Cobb County Board of Tax Assessors determines value; the Tax Commissioner bills and collects the tax. Those are different functions.

If recent comparable sales, permitted improvements, new construction or corrected property information support a higher fair market value, the assessment may change. A finished basement, pool, addition or other improvement can also affect the property record and valuation.

Review the property description as well as the value. Check the square footage, basement finish, acreage and listed improvements.

Remember that the assessor’s value is for taxation. It is not automatically the same as a broker’s comparative market analysis, an appraisal for lending or the price a buyer would offer today.

Your exemptions may be different

Homestead exemptions can reduce taxable value, but they are not automatic in every situation.

Cobb County says applicants generally must own, occupy and claim the home as their legal residence as of January 1. Residents inside a city may also need to apply separately for city exemptions. The county instructs owners to report changes such as moving, selling the property, beginning to rent it or otherwise losing eligibility. Cobb County Tax Commissioner

Cobb also has an existing floating homestead exemption that county officials describe as more generous than the statewide HB 581 exemption for the county’s applicable taxes. That protection does not mean every line on every homeowner’s bill is permanently frozen. School, municipal and special-district taxes may be governed by different rates and exemptions. Cobb County Government

If you recently purchased the home, do not assume the previous owner’s exemption or tax total will carry forward. Confirm that your own applications were accepted and note which taxing authorities each exemption covers.

Marietta homeowners can receive two bills

Location matters.

Cobb County states that properties within Acworth, Austell, Kennesaw, Mableton, Marietta, Smyrna and Powder Springs generally receive both a county bill and a separate city bill. A Marietta mailing address alone does not establish whether a home is inside the incorporated city limits, so verify the parcel’s tax district. Cobb County Tax Commissioner

For 2026, Cobb County property-tax payments are due October 15. The City of Marietta states that its separate 2026 property-tax payment deadline is October 31. City of Marietta Tax Division

If an expected bill has not arrived, retrieve it from the appropriate tax office rather than waiting.

Your mortgage payment may change later

Homeowners with an escrow account may not pay the tax office directly, but the increase still matters.

After the mortgage servicer pays the bill, it reviews the escrow account. If the account is projected to have a shortage, the servicer may increase the monthly payment, request a lump-sum shortage payment or offer a combination of the two, subject to applicable rules and the loan documents.

Review the annual escrow analysis carefully. Confirm that the servicer used the correct bill and credited any payment you made independently. Avoid paying a tax bill yourself without first checking whether the mortgage company has already scheduled payment.

Can you appeal the bill now?

The assessment and the tax bill are connected, but they are not appealed at the same time.

Georgia’s property-assessment appeal must generally be filed with the county Board of Tax Assessors within 45 days of the date on the annual Notice of Assessment. The tax bill arriving later does not restart that deadline. Georgia Department of Revenue appeal form

If an assessment is already under appeal, Cobb says the tax bill will show a regular amount and a lower appeal amount. At least the appeal amount must be paid by October 15. An appeal also does not automatically erase the eventual balance if the final value supports more tax.

If the 45-day window has passed, confirm your options directly with the assessor or qualified property-tax counsel. Do not assume that ignoring the current bill preserves a future challenge.

What homeowners should check now

Before paying, take ten focused minutes and verify:

1. Parcel and tax district: Is the property assigned to the correct jurisdiction?
2. Fair market and assessed values: Does the bill match the assessment notice?
3. Property details: Are the physical characteristics accurate?
4. Exemptions: Are all approved county and city exemptions shown?
5. Multiple bills: Should you expect both county and municipal bills?
6. Appeal status: If an appeal is pending, is the appeal amount displayed?
7. Escrow: Is your mortgage servicer responsible for payment?
8. Deadline: Will payment be received or properly postmarked on time?

Do not compare only with a neighbor’s bill. Two similar homes can carry different taxable values because of purchase dates, exemptions, jurisdictions and appeal histories.

Property taxes belong in every real estate strategy

For buyers, the seller’s current bill may not predict the first full year of ownership. For homeowners, taxes affect monthly affordability and the net return on improvements. For investors, the homestead status and operating tax burden can materially change cash flow.

Property taxes are not a footnote to the transaction. They are part of the cost of owning the asset and should be evaluated with the same care as financing, insurance and maintenance.

If you are buying, selling or reviewing your real estate position in Cobb County, Jules Harper and The Four Walls Group can help you examine the property record, understand the market value and bring the right tax, lending or legal professionals into the conversation.

The goal is not simply to own real estate. It is to understand what you own, protect it wisely and make every decision with the full picture in view.