Quarterly Estimated Tax Calculator for the Self-Employed
Every other estimated tax calculator opens by asking what you will earn this year, which in April you cannot know. The law does not make you guess. Pay 100 percent of last year's tax, 110 percent if last year's AGI was over $150,000, and no underpayment penalty can reach you however this year turns out. That number is already printed on the return in your drawer.
Worked example
These are the figures the calculator opens with and the answer it gives. Change anything above and every number below moves with it.
- Total tax on last year's return21400 $
- Last year's adjusted gross income94000 $
- Filing status this yearSingle, joint, or head of household
- Tax you expect this year, 0 if unknown0 $
- Income tax withheld this year0 $
- Estimated payments already made0 $
- Due dates already gone byNone yet, it is before April 15
Each payment$5,350.00
This year's expected tax is blank, so the answer is the prior year safe harbor and nothing else. That is the safe direction and it is the whole point of doing it this way: the figure can only be larger than the law strictly requires, never smaller, so the penalty cannot reach you even if you earn far more than last year. The one thing it cannot do is test the $1,000 floor, which needs this year's number, so it is possible you owe nothing at all.
This covers the whole tax on your return and not one part of it. Last year's total tax on line 24 already had income tax, self-employment tax and everything else inside it, so do not work out self-employment tax separately and add it on top of this.
Paid by mail, the postmark is the date of payment, and the IRS has clarified that the postmark date is when the item is processed at a postal facility rather than when you dropped it in the box. Paying electronically takes the question away.
State estimated tax is separate, has its own dates in a lot of states, and is not in this number.
| Required for the year | $21,400.00worksheet line 12c, off last year's return alone. Pay this and the penalty cannot apply, whatever this year turns out to be |
|---|---|
| 100% of last year | $21,400.00line 12b. Last year's return has to have covered all twelve months for this leg to be available at all |
| 90% of this year | not enteredline 12a. Left out, so the answer comes off last year alone: larger than the law needs, and safe from the penalty |
| To pay in estimates | $21,400.00line 14a, the required annual payment less any withholding |
| April 15, 2026 | $5,350.001st payment, one fourth, and Form 2210 uses that same one fourth in every column |
| June 15, 2026 | $5,350.002nd payment |
| Sept. 15, 2026 | $5,350.003rd payment |
| Jan. 15, 2027 | $5,350.004th payment, and you can skip it by filing the return by February 1, 2027 and paying the balance with it |
What this calculator assumes
- Estimated tax is how somebody without an employer pays tax across the year. Nothing is withheld from a 1099 or from business profit, so the law asks for four payments instead, and Form 1040-ES is the form that works out how much.
- The required annual payment is the smaller of two things: 90 percent of the tax you will owe this year, or 100 percent of the tax you owed last year. Pay the smaller of the two and no underpayment penalty applies, however the year actually turns out.
- That second leg is the reason this page does not ask you to forecast your income. Last year's total tax is Form 1040 line 24, a number already printed on a return you have. Everything on this page can be worked out from it and from nothing else.
- The prior year leg is only available if last year's return covered all twelve months. A part year first return does not qualify for it.
- Above $150,000 of last year's AGI, or $75,000 if you file married filing separately, that leg is 110 percent of last year rather than 100 percent.
- The four dates are April 15, June 15, September 15 and January 15 of the next year. Everybody calls them quarterly and they are not: that is a three, two, three then four month spread. The reason is that the periods underneath them are cumulative windows of 3, 5, 8 and 12 months, not four equal quarters.
- Each required installment is one fourth of the required annual payment, the same figure in all four columns of Form 2210. Missing one does not re-spread the rest, and a payment is applied to the oldest shortfall first whatever period you write on it.
- The January payment can be skipped if you file the return by February 1 and pay the whole balance with it.
- The figure covers the whole tax on your return. Last year's total tax already had income tax, self-employment tax and everything else inside it, so this is not a self-employment tax number with income tax still to come.
- What is not here: the penalty itself, which is the federal short-term rate plus 3 points and is re-announced every quarter by news release, so a figure printed for it would go stale quietly. Also the farming and fishing two thirds rule, household employers, fiscal year filers, and state estimated tax, which has its own dates.
- The wording and the figures come from Form 1040-ES for 2026, Publication 505 for 2026 and the Instructions for Form 2210, captured in tools/statutes/irs-estimated-tax.txt.
You are allowed to ignore this year completely
Form 1040-ES sets the required annual payment as the smaller of two things: 90 percent of the tax you will owe this year, or 100 percent of the tax you owed last year. Most calculators build themselves around the first one, which is why they all start by asking you to forecast an income you have not earned yet.
The second leg needs one number, the total tax on last year's return, Form 1040 line 24. Not what you sent in with it, not your income, the whole tax for the year. Pay that across the four dates and the penalty cannot apply even if you go on to have the best year of your life, because the law measures you against last year and last year is already settled.
There is a price and it is worth naming. If this year is quieter than last year you will have paid more than you strictly had to, and you get it back as a refund rather than keeping it in the business in the meantime. What you buy for that is certainty, and for a contractor whose December is nothing like their April it is usually a good trade.
Above $150,000 the safe harbor costs 10 percent more
If last year's adjusted gross income was over $150,000, or over $75,000 if you file married filing separately, the prior year leg becomes 110 percent of last year's tax instead of 100 percent. It is a hard edge, not a slope: one dollar of AGI over the line moves the whole calculation.
The threshold looks at last year's AGI and the filing status you are using this year, which are two different years in the same sentence and is easy to read past. Put both in and the page applies the right one.
The 90 percent leg is unaffected by any of this. So the higher your income the more often it is the current year leg that ends up smaller, and the more it is worth putting in an estimate of this year even a rough one, because it can only lower the answer and never raise it.
They are called quarterly and they are not
The dates are April 15, June 15, September 15 and January 15 of the following year. That is three months, then two, then three, then four. Nobody mistypes this: the periods underneath the dates are cumulative windows of 3, 5, 8 and 12 months, so the second one closes at the end of May and the third at the end of August.
It matters as soon as your income is uneven, which for anybody working outdoors it is. Money earned in July sits inside the period that closes on August 31 and has to be covered by the September payment, not by the one in January.
The January payment is the one with an escape. File the return by February 1 and pay the whole balance with it, and that payment does not have to be made at all.
What actually happens when you miss one
Two things about a missed payment are not what almost anybody assumes. The first is that the charge is worked out on the number of days each shortfall stays unpaid. It behaves like interest rather than a fine, so there is no cliff to fall off and paying three weeks late costs roughly three weeks worth. Late is much better than never and a lot better than waiting for the next date.
The second is that a payment lands on the oldest shortfall first, whatever period you write on the voucher. You cannot leave April unpaid, send a big January payment, and have April treated as covered from January. April keeps running until enough money has arrived to fill it, which is why catching up early is worth more than catching up large.
And the required installment never re-spreads. Form 2210 puts one fourth of the required annual payment in every one of its four columns. Missing one does not make the other three bigger and paying one twice over does not make the next one smaller.
If the work had not started yet, there is a different form
A contractor who takes no money in the first quarter and then has a full summer is not the person these four equal payments were designed for, and the IRS knows it. Its own first example of uneven income is a business operated on a seasonal basis.
The answer is the annualized income installment method on Schedule AI of Form 2210. It works out each installment from the income you had actually received by the end of each period, so income earned in August cannot make the April installment late. It can lower an earlier installment or remove it completely.
It costs you something: you have to use it for all four due dates once you use it for any of them, it needs your income period by period rather than as a yearly figure, and you have to file Form 2210 with the return even when no penalty is owed. This page does not compute it, because it needs month by month figures this page does not ask for. It is named here so that the right people go and look at it.
This is your whole tax, not the self-employment part
Last year's total tax on line 24 already had everything in it: income tax, self-employment tax, any additional Medicare tax, the lot. So the figure on this page covers all of them. Work out self-employment tax separately and add it on top and you will be paying it twice.
That is the difference between this page and the self-employment tax calculator, which answers a narrower question: what social security and Medicare come to on your business profit alone. Its own last row hands you a quarterly figure for that one tax, and income tax is still on top of it.
State estimated tax is separate again. A good many states want their own payments on their own dates, and none of that is in this number.
Questions people ask
How do I work out quarterly taxes without knowing what I will earn?
You do not have to know. The required annual payment is the smaller of 90 percent of this year or 100 percent of last year, so paying 100 percent of last year's total tax, 110 percent if last year's AGI was over $150,000, avoids the penalty whatever this year turns out to be. Last year's total tax is Form 1040 line 24.
When are estimated taxes due?
April 15, June 15, September 15 and January 15 of the following year. They are not three months apart, because the periods underneath them are cumulative windows of 3, 5, 8 and 12 months. The January payment can be skipped if you file the return by February 1 and pay the balance with it.
Do I have to pay estimated tax at all?
Only if you expect to owe at least $1,000 after your withholding, and your withholding is less than the smaller of the two legs. If you had no tax at all on a last year's return that covered twelve full months, no estimated tax is required this year however much you earn.
What happens if I miss a payment?
The charge runs on the number of days the shortfall stays unpaid, so it is closer to interest than to a fine and paying as soon as you can costs less. A payment is applied to the oldest shortfall first even if you label it for a later period, so a missed April cannot be covered by a larger January payment.
Is this the same as self-employment tax?
No. This is the payment, and it covers your whole tax bill: income tax, self-employment tax and everything else on the return together. Self-employment tax is one component of it, and the self-employment tax calculator works out that one on its own.
Free Contractor Invoice Template, free, no signup, PDF Word and Excel.