How to Calculate Quarterly Estimated Taxes
If you are self-employed, freelancing, or earning 1099 income, the IRS expects you to pay tax as you earn it, not in one lump next April. That means four estimated payments a year. The good news: you do not have to predict your exact tax bill. You just have to hit a safe harbor and pay on time. This guide shows you how to size each payment, when each one is due, and how to dodge the penalty that trips up most first-timers.
Do you even have to pay estimated taxes?
Generally, you owe estimated taxes if you expect to owe at least $1,000 in tax for the year after subtracting your withholding and refundable credits. If your side income is small or your day-job withholding already covers your bill, you may be off the hook. If you clear that bar, read on. Confirm the current threshold on IRS.gov, since the IRS can adjust it.
The four 2026 payment deadlines
Estimated taxes are due four times a year, and the "quarters" are not even three-month blocks. Mark these dates for the 2026 tax year:
- Q1 (income earned Jan 1 to Mar 31): due April 15, 2026
- Q2 (Apr 1 to May 31): due June 15, 2026
- Q3 (Jun 1 to Aug 31): due September 15, 2026
- Q4 (Sep 1 to Dec 31): due January 15, 2027
When a deadline lands on a weekend or holiday, it shifts to the next business day. Always confirm the exact dates on IRS.gov before you pay, since the IRS occasionally adjusts them. One useful out: you can skip the Q4 (January) payment if you file your full return and pay the entire balance by the IRS's early-February deadline.
The two safe-harbor rules (so you stop guessing)
You will not owe an underpayment penalty if your total payments for the year cover the smaller of two thresholds. This is the heart of the whole system:
- 90% of your current-year tax. Pay at least 90% of what you will actually owe this year.
- 100% of last year's tax (or 110% if your prior-year adjusted gross income was above a threshold set by the IRS). This is based on the total tax on last year's return, which you already know.
The second rule is the freelancer's friend. Because it uses a number that is already settled, you never have to forecast a year you cannot see yet. If you expect to earn less this year, the 90% rule may be cheaper; if you expect to earn more, locking in last year's number protects you no matter how good the year gets. Confirm the current AGI threshold for the 110% tier on IRS.gov, as it can change. (Using last year's tax also requires that your prior year was a full 12-month tax year.)
How to split the total into four payments
Once you have a target total, the default method is the simplest: divide it by four and pay one quarter each deadline. Here is the workflow:
- Estimate your full-year tax. Use the tax estimator to project your federal income tax. Remember to add self-employment tax (Social Security and Medicare on net self-employment earnings), which the income-tax estimate alone does not include.
- Pick your safe harbor. Compare 90% of that current-year estimate against 100% or 110% of last year's total tax, and target the smaller number.
- Divide by four. That is your per-quarter payment.
- Subtract withholding. If you also have a W-2 job or your spouse does, paycheck withholding counts toward your total. Estimate that with the paycheck calculator and only send estimates for the gap.
If your income is lumpy (a huge Q3, a quiet Q1), you can use the IRS annualized-income method to pay more in big quarters and less in slow ones. It is more paperwork, but it can lower penalties when earnings are seasonal.
A worked example
Say you are a freelancer whose total tax last year was $20,000, and your prior-year AGI put you in the 110% tier. This year is shaping up bigger: the tax estimator projects roughly $22,000 in total tax (income tax plus self-employment tax).
Run both safe harbors:
- 90% of current year: 0.90 × $22,000 = $19,800
- 110% of last year: 1.10 × $20,000 = $22,000
The smaller threshold is $19,800, so that is your safe-harbor target. Divide by four:
$19,800 ÷ 4 = $4,950 per quarter
You send $4,950 on each of the four deadlines, total $19,800. Even if your actual tax comes in at $22,000, you have met the 90% safe harbor, so no underpayment penalty applies. You simply pay the remaining roughly $2,200 when you file. Note: hitting a safe harbor avoids the penalty, not the tax. The balance is still due by the April filing deadline.
The pay-as-you-go penalty trap
Here is the gotcha that surprises people: the penalty is calculated quarter by quarter, not on the year as a whole. If you skip Q1 and Q2 and then dump the full year's amount in December, the IRS still charges an underpayment penalty for the quarters you missed, even though you "paid in full." The system is pay-as-you-go, and each missed deadline accrues interest from that date.
The penalty is effectively interest at a rate the IRS sets each quarter, so it is not catastrophic, but it is pure waste. Two ways to avoid it entirely:
- Pay each quarter, on time, every time. Set calendar reminders for all four dates the moment you read this.
- Increase W-2 withholding instead. Withholding is treated as paid evenly across the year no matter when it happens. If you (or a spouse) have a W-2 job, bumping up withholding late in the year can retroactively cover earlier quarters, something estimated payments cannot do.
Pay online through IRS Direct Pay or EFTPS so you have a timestamped confirmation for each quarter. Do not forget state estimated taxes, which most states require separately on their own schedule.
Quick decision guide
Not sure where to start? If you had a tax bill last year, the safest move is to target 100% or 110% of that known number, split it in four, and pay every deadline. If this is your first year of self-employment with no prior return to lean on, estimate current-year tax with the tax estimator, aim for 90%, and set aside roughly a quarter to a third of each payment you receive so the cash is there when the deadline arrives. For more on how the underlying tax is computed, see our guide on how to calculate taxes.
These figures are estimates for planning, not professional tax advice. Tax rules, thresholds, and rates change. Confirm current numbers on IRS.gov and consult a tax professional or CPA for your specific situation, especially in your first year of self-employment.
Frequently Asked Questions
You will owe an underpayment penalty for that quarter, calculated as interest from the missed deadline until you pay, even if you pay the full year's tax later. The penalty is quarter-by-quarter, so paying in full by April does not erase a skipped Q1 or Q2. Catch up as soon as possible to stop the interest from growing.
With no prior year to lean on, estimate your full-year tax using a tax estimator, including self-employment tax for Social Security and Medicare. Aim to cover at least 90% of that projection, divide by four, and pay each deadline. A common rule of thumb is to set aside 25% to 30% of every payment you receive so the cash is ready.
Yes. Your quarterly payments should cover both federal income tax and self-employment tax, which funds Social Security and Medicare on your net self-employment earnings. A federal income-tax estimate alone understates what you owe. Add the self-employment portion before splitting the total into four payments, or you will fall short of the safe harbor.
Often, yes. Withholding is treated as paid evenly across the year no matter when it actually happens, so if you or a spouse have a W-2 job, raising withholding can cover your self-employment tax and even retroactively fix earlier quarters. That timing flexibility is something estimated payments cannot match, which makes it a useful penalty fix late in the year.
You avoid the underpayment penalty if your payments cover the smaller of 90% of your current-year tax or 100% of last year's total tax (110% if your prior-year AGI exceeded the IRS threshold). Targeting last year's known number is easiest because you do not have to forecast. Confirm the current AGI threshold on IRS.gov, as it is adjusted over time.