How much estimated tax do I pay each quarter?

Start with the year, not the quarter. At the inputs above, $120,000 of expected self-employment profit filing single, the engine projects a real 2026 Form 1040: half the self-employment tax comes off as an adjustment, leaving $111,522 of adjusted gross income, then the standard deduction of $16,100 leaves $95,422 of taxable income and $15,706 of income tax. Self-employment tax of $16,955 is added on top, because nobody withheld Social Security and Medicare for you. Total tax for the year: $32,661.

Then the law asks for less than all of it. The required annual payment is the lesser of 90% of this year's tax, $29,395, and 100% of your 2025 tax, $26,000. Here that is $26,000. Expected withholding of $0 comes off next, leaving $26,000 for the four installments to carry, which is $6,500 each.

That last division is the whole schedule under the standard method: four equal installments, 25% of the requirement each, with the odd cent landing on the early quarters. The alternative, the annualized income installment method, prices each period on the income you actually earned in it and is worth using if your income is lumpy. This calculator does not compute it, and says so below rather than pretending the even split is always right.

The underpayment penalty is not charged on being wrong about the year. It is charged on paying less than the required annual payment, and the required annual payment is capped by last year's tax, a number you already know exactly. That is the asymmetry worth exploiting: pay 100% of your 2025 tax and the penalty is off the table even if this year doubles. You will owe the difference in April, but you will owe it without interest for the underpayment.

Which leg binds depends on the direction your year is moving. A year that is growing takes the prior-year leg: at the inputs above, $29,395 is 90% of this year's projection and $26,000 was last year's whole tax bill, so the requirement is the smaller $26,000. A year that is shrinking takes the other one. A single filer whose 2025 tax was $45,000 but who expects only $60,000 of profit this year owes $12,991, so 90% of it is $11,692 against a prior-year test of $49,500. The calculator takes the $2,923 quarterly payment, not the $12,375 one.

The cheaper leg is also the riskier one. The 90% test moves with your actual income, so if the year comes in above your estimate the target rises underneath you and payments made on old assumptions fall short. The prior-year leg is fixed the day you file last year's return. When the calculator selects the current-year leg it says so in a warning under the answer.

This is the detail most quarterly tax calculators leave to the reader. Above an AGI line, § 6654(d)(1)(C) raises the prior-year safe harbor from 100% of last year's tax to 110% of it. The line is $150,000 of prior-year adjusted gross income for every status except married filing separately, where it is $75,000. It is a cliff, not a phase-in. One dollar of AGI decides it.

Same expected income, same 2025 tax bill of $26,000, same filing status. At $100,000 of prior-year AGI the requirement is $26,000 and each payment is $6,500. At $150,001, one dollar over the line, the requirement is $28,600 and each payment is $7,150, a difference of $650 every quarter. A reader who paid 100% because an article told them 100% is the rule would be short $2,600 for the year and exposed to the penalty they were trying to avoid.

Filing status moves this line too, which is why the calculator prices all five. On the inputs above, a 2025 AGI of $93,000 sits under the $150,000 threshold for every status except married filing separately, where the threshold is $75,000 and the same taxpayer owes $7,150 a quarter instead of $6,500.

Apr 15, 2026, Jun 15, 2026, Sep 15, 2026, Jan 15, 2027. Two things about that list surprise people. The periods are not equal: the second covers two months, not three. And the last one falls in the following calendar year, which means the final payment for 2026 is due Jan 15, 2027, before you file the return it belongs to.

The penalty is computed per period, not on the year. Paying nothing until December and then sending the whole $26,000 does not undo a missed Apr 15, 2026 payment: interest runs on each shortfall from its own due date. That is the practical reason the schedule below shows four separate amounts rather than one annual figure.

Withholding is the exception, and it is a useful one. Federal income tax withheld from a paycheck is treated as paid evenly across the year no matter when it was actually withheld, so raising withholding late in the year can repair an early shortfall in a way an estimated payment cannot. If you have any W-2 income at all, a new Form W-4 is often a better fix than a catch-up payment.

There is a floor. Under § 6654(e)(1) no estimated tax is required if your expected tax for the year, after withholding and refundable credits, is under $1,000. A single filer with $6,000 of profit and no withholding owes $848, almost all of it self-employment tax, since the standard deduction of $16,100 wipes out the income tax entirely. That is under the floor, so this calculator returns $0 for all four quarters and tells you why rather than asking for $191 a quarter you do not owe.

There is a second exception the calculator does not need an input for: § 6654(e)(2) excuses you if you had no tax liability at all last year, on a return that covered a full twelve months, and you were a citizen or resident for the whole year. Leaving the 2025 total tax at zero here removes the prior-year safe harbor rather than claiming that exception, because the two are different questions and only your return answers the second one.

The penalty itself. This page names the amount that avoids the penalty; it does not compute the penalty you already owe. The engine is explicit about that limit rather than silent: "Filing-grade underpayment penalty computation is blocked until final TY2026 Form 2210, FTB 5805, or New York penalty support is packeted.". If you have already missed a payment, the figure you need comes from Form 2210, not from here.

Uneven income. The schedule above assumes four equal installments. If your income arrives in bursts, a summer contract or a December close, the annualized income installment method prices each period on what you actually earned in it and usually asks for less early in the year. The engine refuses that method by name rather than approximating it, so this page does not offer it as an input.

Farmers and fishers, who get their own schedule under § 6654(i), one installment instead of four. State and local estimated tax, which California and New York both require on their own dates and their own safe harbors. And anything past a Schedule C profit plus W-2 wages on the standard deduction: capital gains, rental income, retirement distributions, itemized deductions, and the qualified business income deduction all change the 2026 tax this schedule is built on. 2026 has no certified annual forms yet, so the projected return is computed on the current-law parameter set for the year and is planning-grade, not filing-grade. None of it is tax advice.

This calculator is built to be used without a browser. Every input is a query parameter on this page, and the same parameters on the JSON twin return the complete answer as a document.

GET /tools/estimated-taxes.json?income=200000&priorTax=40000&priorAgi=185000

The response carries inputs after parsing and clamping, result with the quarterly installment, the selected safeHarbor with the basis the statute dispatched to, installments with each due date, required amount, credited payments and shortfall, the required annual payment before and after withholding, the projected form1040 lines behind the expected tax, plus sensitivity across an income ladder, a prior-year AGI ladder that straddles the 110% threshold, and all five filing statuses, and the engine's own diagnostics and nonClaims, drivers ranked by effect with a plain sentence each, assumptions that say for every field whether you supplied it and name the source when the default came from one, sources with a URL and an as-of date for each source the tool cites, which is an empty list on the calculators whose every default is an example input rather than a published figure, warnings, a disclaimer, and in tool the canonicalUrl and jsonUrl that carry only your non-default parameters. The canonical URL is the answer's permanent address; use it when you cite the number.

Parameters, all optional, in any order:

• income ($ per year), default $120,000 per year.
• withholding ($ per year), default $0 per year.
• priorTax ($ per year), default $26,000 per year.
• priorAgi ($ per year), default $93,000 per year.
• wages ($ per year), default $0 per year.
• paid ($ per year), default $0 per year.
• status (one of single, married-joint, married-separate, head-of-household, qualifying-surviving-spouse), default single.

Values accept plain numbers and loose human formats such as 100k, $100,000, or 6.5%. Unknown parameters are ignored, values outside a field's range are clamped and reported in warnings, and the endpoint never fails on bad input. Responses are cacheable for a day; the defaults change when their sources publish, and tool.version changes when the method does.

• IRS Form 1040-ES (2026), Estimated Tax for Individuals, as of 2026-01-01. The worksheet that computes the required annual payment and the four 2026 installment due dates. The engine cites it for every installment it prices.
• IRS Publication 505, Tax Withholding and Estimated Tax (2026), as of 2026-01-01. The prior-year safe harbor, the $1,000 threshold below which no estimated tax is required, and the rule that withholding counts as paid evenly across the year.
• 26 U.S.C. § 6654 (failure by individual to pay estimated income tax), as of 2026-01-01. The statute itself: § 6654(d)(1)(B) makes the required annual payment the lesser of the two safe harbors, § 6654(d)(1)(C) sets the 110% high-income variant, and § 6654(e) sets the exceptions.
• IRS Rev. Proc. 2025-32 (2026 inflation-adjusted items), as of 2026-01-01. The rate tables and standard deduction for tax year 2026, which is what the expected-tax half of this page is computed on.
• One Big Beautiful Bill Act (P.L. 119-21), as of 2025-07-04. The statute behind the current standard deduction and rate structure the 2026 projection uses.

These are the authorities the engine itself reports, not citations chosen after the fact. The installment plan cites Form 1040-ES and Publication 505 for every payment it prices; the projected 2026 return cites the revenue procedure and the statute that set this year's rates and standard deduction. When the engine loads a different parameter set, this list changes with it.

Carlo is a personal finance agent. It knows your accounts, debts, and goals, so instead of a projection from the profit you typed it can watch what you actually invoice and withhold through the year, and tell you before each of those four dates whether the payment you set in April is still the right one. Text it the question.

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