September 15 is two deadlines, not one.
Most owners in Marietta and East Cobb have the federal installment on their calendar. Far fewer have the second one, because Georgia runs its own estimated tax system, with its own form, its own filing test and its own set of penalty exceptions. Being current with the IRS does not settle the state, and this year the state side changed in a way that quietly moved every voucher.
If you want the federal mechanics, we covered the safe harbor rules in a separate post. This one is about Georgia estimated tax payments: what the state expects, and what Cobb County business owners should check before the September installment goes out.
Georgia has its own estimated tax system
Georgia estimated tax payments are collected from individuals and fiduciaries on Form 500-ES. The installment dates track the federal calendar — April 15, June 15, September 15, and January 15 of the following year, rolling to the next business day when one falls on a weekend or holiday — but that is where the similarity stops.
Payments go to the Georgia Department of Revenue, either through the Georgia Tax Center or by mailing the voucher. They are separate from anything you send the IRS, and they are tracked separately. A common pattern we see in East Cobb: an owner who has been diligent about federal payments for years and has never made a Georgia one, because nobody told them there were two.
Who actually has to file Form 500-ES
The Department of Revenue frames the requirement around expected gross income rather than expected tax. In the Department’s wording, an individual or fiduciary subject to Georgia income tax must file estimated tax if they reasonably expect gross income during the year to exceed the total of their applicable exemptions, their estimated deductions, and $1,000 of income not subject to withholding.
In practice, that captures most of the people reading this:
- A consultant or contractor in East Cobb paid on 1099 income with no withholding.
- An owner taking distributions from a Marietta S corporation.
- A landlord with rental income from property around Cobb County.
- A household with one W-2 job and one side business, where the W-2 withholding does not cover the extra income.
There is a useful exception in the instructions. If you and your employer agree to withhold additional tax to cover income that would otherwise require estimated payments, the estimated tax filing is not required. For a Cobb household with one salaried spouse and one self-employed spouse, adjusting the W-4 is often simpler than remembering four separate payment dates, and it is worth pricing out before defaulting to vouchers.
Georgia’s penalty exceptions are not the federal ones
This is where people get caught. The federal thresholds most owners can recite — 90% of the current year, 100% of last year, 110% above a certain income level — do not apply to Georgia.
Georgia computes underpayment on Form 500 UET, and it works from a different set of figures. The required installments are measured against the lesser of two amounts: 70% of the current year’s tax, or 100% of the immediately preceding year’s tax, provided that year covered a full twelve months and a return was filed. There is also an annualized-income exception for owners whose income arrives unevenly across the year, which is genuinely useful for seasonal businesses and anyone paid on commission.
Where the numbers land short, Georgia adds 9% per year on the underpayment, computed installment by installment from each due date. That rate is set in the statute rather than reset quarterly the way the federal rate is, and because it accrues by the day, catching up the moment you notice a gap costs materially less than settling it at filing.
The consequence is that you can be perfectly clean federally and short in Georgia, or the reverse. Nothing in the Georgia rules treats a satisfied federal safe harbor as satisfying the state, so using one calculation as a proxy for the other is the single most common estimated tax error we correct for new clients.
The 2026 change that moved every Georgia voucher
House Bill 463 was signed on May 11, 2026 and cut Georgia’s flat individual income tax rate from 5.19% to 4.99% for tax years beginning on or after January 1, 2026. The same bill raised the standard deduction to $15,000 for single filers and $30,000 for married couples filing jointly, and raised the dependent deduction to $5,000.
Now think about where your April and June vouchers came from. If they were built in January off a worksheet using last year’s rate and last year’s deduction — which is how most estimated payments get calculated — they were computed at 5.19% against a smaller deduction. They were almost certainly too high.
The same thing happened inside payroll. Employers were required to keep withholding at 5.19% until the bill took effect and could only move to 4.99% from May 11, so the wages your household earned in the first four months of the year were over-withheld against the rate that now applies for the whole year. If one spouse is salaried and the other is self-employed, both sides of the household are running ahead of the state.
A lot of Cobb County owners are quietly ahead on Georgia right now and have no idea. The September installment is where that gets corrected, and correcting it is not the same as skipping it. The right move is to rebuild the projection at the current numbers and pay whatever the rebuilt figure actually calls for.
Tips and overtime: Georgia and the IRS now diverge
One more wrinkle that matters more in Cobb County than most places, given how many restaurants, trade contractors and service businesses operate here.
Georgia did not adopt the federal treatment of tip and overtime income. It built its own, and the two work differently in both size and mechanism.
At the federal level, qualified tips and qualified overtime are deductions, and the caps are large: up to $25,000 for tips, and up to $12,500 for overtime, or $25,000 for joint filers. Georgia instead allows exclusions from Georgia taxable net income, capped at $1,750 of qualified overtime compensation and $1,750 of cash tips, for tax years 2026 through 2028.
The qualifying conditions are narrower than most people assume, too. Georgia’s overtime exclusion applies to a full-time employee paid an hourly wage. The tip exclusion applies to cash tips that are voluntary, not negotiated, and determined by the payer, in an occupation on the Treasury list of tipped occupations. A salaried manager’s extra hours and a mandatory service charge on a large party are both outside it.
So for a restaurant on Marietta Square, or a trade crew running consistent overtime through the summer, the federal projection and the Georgia projection genuinely produce different taxable income. If you built your Georgia estimate by taking your federal number and multiplying by the state rate, this is the year that stops working.
What to check before the September installment
- Pull your 2025 Georgia Form 500 and find the total tax. That is the 100% prior-year figure the exception is measured against.
- Rebuild the 2026 projection at 4.99%, using the 2026 standard deduction and dependent deduction amounts rather than last year’s.
- Compare that against what you actually paid in April and June. If you are ahead, adjust September down rather than paying on autopilot.
- Calculate Georgia separately from federal. Do not derive one from the other, particularly if tip or overtime income is in the mix.
- If you own an S corporation or a partnership, confirm whether the entity has made Georgia’s pass-through entity election before you send anything personally. When that election is in place the entity makes its own estimated payments, and personal estimates sent on top of them cannot be moved across to the entity — the overpayment has to come back through your individual return instead. Check the election status first, not after the voucher clears.
- If you missed the April or June installment, pay the shortfall now rather than waiting for the next date. The charge runs from the installment due date, so catching up early costs less than catching up at filing.
- Schedule the payment in the Georgia Tax Center a day or two ahead of the deadline rather than on the afternoon of the 15th, and queue the January 2027 installment while you are already logged in.
Working with our Marietta team
Our Marietta office on Shallowford Road works with owners across East Cobb, Kennesaw, Woodstock and the surrounding area, and estimated tax is one of the most common reasons someone calls us for the first time. Usually it is one of three situations: they have never made a state payment, they have been paying a number nobody has revisited in three years, or they have just realized the two systems do not agree.
All three are fixable, and all three are cheaper to fix before a deadline than after one. If you are not sure which one describes you, that is a short conversation rather than a project. Our tax planning and business tax teams handle both sides of it.
Frequently asked questions
Do I have to make Georgia estimated payments if I already pay the IRS?
Yes, if you meet Georgia’s filing test. The two systems are separate. Federal payments are not credited against Georgia liability, and meeting a federal exception does not protect you from a Georgia underpayment charge.
What are the Georgia estimated tax due dates for 2026?
April 15, June 15 and September 15 of 2026, and January 15 of 2027. If a date falls on a weekend or a legal holiday it moves to the next business day. The schedule mirrors the federal calendar, which is why September 15 carries both payments.
I overpaid Georgia in April and June because of the rate change. Can I just skip September?
Possibly, but not automatically. It depends on how far ahead you are against the exception you are relying on, and skipping an installment outright is a different thing from reducing it. Rebuild the projection first and let the number decide.
What happens if I missed the June installment?
Georgia adds 9% per year on the underpayment, computed on Form 500 UET installment by installment from each due date. It accrues by the day until the shortfall is paid, so paying as soon as you notice costs materially less than waiting until you file in April.
Does the pass-through entity election change any of this?
It can change it substantially. If an eligible S corporation or partnership elects to pay Georgia income tax at the entity level, the entity makes the estimated payments at the same rate that applies to individuals, and your personal Georgia estimates should be recalculated. Note that personal payments already made cannot be transferred to the entity, so it is worth confirming the election status before the next voucher rather than after.
Talk to us before the 15th
If you are not certain whether you owe a Georgia installment this month, or whether the one you are about to send is the right number, our Marietta team can check it. Book a consultation and bring last year’s Form 500.
