Quarterly Tax Calculator
How much to send the IRS each quarter: your estimated federal income + self-employment tax, the Form 1040-ES safe harbor that caps what you actually must prepay, and the four due dates for the year. Federal only — many states run their own estimated-tax systems with their own vouchers.
Estimated quarterly payments (2026)
Example: $80,000 freelance profit, prior-year tax $9,000 → $2,250.00 per quarter under the prior-year safe harbor.
The worked example, step by step
A single freelancer expecting $80,000 of Schedule C profit in 2026: self-employment tax comes to $11,303.64, and after subtracting the deductible half ($5,651.82) and the $16,100 standard deduction, the brackets charge $7,526.60 of income tax — $18,830.24 of estimated federal tax in total. The safe harbor is the lesser of 90% of that ($16,947.22) or 100% of the $9,000 prior-year tax ($9,000.00) — so the required annual payment is $9,000.00, or $2,250.00 per installment, due April 15, 2026, June 15, 2026, September 15, 2026, and January 15, 2027. Every figure is computed by the same tested engine as the calculator above. The remaining $9,830.24 is simply owed at filing time, penalty-free, because the safe harbor was met.
Why the safe harbor is the number that matters
The IRS does not require you to prepay your exact tax — it requires the safe-harbor amount: the lesser of 90% of this year's tax or 100% of last year's (110% if last year's AGI topped $150,000). For a freelancer whose income is growing, the prior-year option is the planning gift: last year's smaller tax bill sets this year's required payments, and the growth is settled in April without penalty. These percentages and the $1,000 minimum were verified against IRS Publication 505 (2026) and the Form 1040-ES instructions, which remain the controlling sources.
What feeds the estimate
The current-year estimate reuses this site's engines: the federal bracket math on your AGI after the standard deduction (see where that lands you), plus self-employment tax when you enter freelance profit — including the ½ SE-tax deduction, applied for you. Enter your expected AGI before that deduction; if you also have W-2 wages, put your expected paycheck withholding in the withholding field (estimate it with the Take-Home Pay Calculator). Credits and other taxes are out of scope — the estimate is the federal income + SE core.
Frequently asked questions
Who has to pay quarterly estimated taxes?
Per IRS Publication 505 and the Form 1040-ES instructions, you generally must pay estimated tax if you expect to owe at least $1,000 after subtracting withholding and refundable credits, AND your withholding will be less than the smaller of 90% of this year's tax or 100% of last year's. Freelancers, landlords, and investors with no withholding usually qualify; employees whose W-4 withholding covers the safe harbor usually do not.
What exactly is the "safe harbor"?
The required annual payment is the LESSER of 90% of your current-year tax or 100% of the total tax on last year's return — 110% instead of 100% if last year's AGI was more than $150,000 ($75,000 if married filing separately, a status this calculator does not model). Pay that much through withholding plus timely installments and you avoid an underpayment penalty even if you owe more in April. The prior-year option requires a prior-year return covering all 12 months.
When are the payments due?
For tax year 2026: April 15, 2026, June 15, 2026, September 15, 2026, and January 15, 2027. The general rule is April 15, June 15, September 15, and January 15 of the following year, each shifting to the next business day when it lands on a weekend or legal holiday — the calculator shows the published dates for the year you select. You can skip the January payment if you file your return and pay the balance by January 31.
Why quarterly amounts that are not really quarterly?
The four "quarters" cover Jan–Mar, Apr–May, Jun–Aug, and Sep–Dec — two, three, and four months, not neat calendar quarters. This tool divides the annual shortfall into four equal installments, the standard approach when income arrives evenly. If your income is lumpy (a Q4 windfall, seasonal work), the annualized income installment method on Form 2210 can lower early payments — that method is out of scope here.
Does this calculate the underpayment penalty?
No. Penalty math lives on Form 2210 and depends on exactly when each payment landed and the quarterly interest rates the IRS sets. This calculator answers the planning question — how much to send each quarter to stay inside the safe harbor so no penalty arises in the first place.
What taxes are included in the estimate?
Federal income tax (standard deduction) plus self-employment tax, computed by the same engines as the other calculators on this site. Not included: tax credits, capital-gains rate treatment, the additional Medicare surtax nuances by filing status, household employment taxes, state estimated taxes (many states have their own vouchers and dates), and itemized deductions. If credits or other taxes matter to you, adjust your expected tax accordingly or use the Form 1040-ES worksheet.
Not tax advice: a planning estimate of federal income + self-employment tax only — no credits, no capital-gains rate treatment, no state estimated taxes, no married-filing-separately modeling, no annualized-installment method, and no Form 2210 penalty computation. Safe-harbor rules and due dates verified against IRS Pub. 505 and Form 1040-ES for the supported years; your actual obligations are determined by your full return. Consult a tax professional for your situation. Values are processed locally in your browser and never transmitted. See the methodology page.