Free · Nonprofit · Education only · Updated October 13, 2026

Estimated tax payment calculator for the year of a big sale

A big sale can mean a big tax bill with no withholding. The IRS wants it paid during the year, but how much and when depends on the safe harbor you use and the month you close. Enter your numbers to see each payment, date by date, and what is still due in April 2027.

By , founder, Retirement Literacy Foundation. 2026 federal law, every rate sourced below.

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Capital gains estimated tax calculator

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Worked example

A 2026 example, worked out

A married couple in California closes the sale of a rental in September 2026 with a $900,000 long-term gain, $150,000 of it depreciation. Their other income is $180,000, with $22,000 withheld. Their 2025 tax was $32,000 on $210,000 of AGI.

LineAmount
Federal estimated tax to pay for 2026$13,200
Pay by April 15, 2026$0
Pay by June 15, 2026$0
Pay by September 15, 2026$0
Pay by January 15, 2027$13,200
Even 25% schedule instead (each)$3,300
Total 2026 federal tax (incl. NIIT and any AMT)$223,993
Of that, caused by the sale$202,053
Balance still due with your return by April 15, 2027$188,793
90% of 2026 tax$201,594
Prior-year safe harbor (110% of 2025 tax)$35,200
Federal withholding you expect$22,000
California tax for 2026 (sale adds $89,413)$97,969

Computed October 13, 2026 with the same engine the calculator uses: 2026 federal brackets (IRS Rev. Proc. 2025-32), state rates as coded for 2026. Illustrative; your numbers will differ.

How it works

The rules behind the numbers

  1. Two safe harbors. You avoid the underpayment penalty if withholding plus estimated payments cover the smaller of 90% of this year's tax or 100% of last year's tax, 110% if last year's AGI was over $150,000 ($75,000 married filing separately) (IRC 6654(d)(1)).
  2. The prior-year safe harbor is the big-sale shortcut. In the year of a big sale, 110% of last year's tax is usually far less than 90% of this year's. Pay that on time and there is no penalty, even though a large balance is due with your return. Plan for that balance: it is due April 15, 2027.
  3. Four dates for 2026. April 15, 2026; June 15, 2026; September 15, 2026; January 15, 2027 (IRS Form 1040-ES (2026)). Each covers a period: January to March, April and May, June to August, September to December.
  4. Closing late in the year? Annualize. The annualized income installment method figures each payment from income actually received by the end of each period. A September closing puts the sale in the last period, so the payment for it is due January 15, 2027 instead of being owed back to April. You attach Form 2210 with Schedule AI (Instructions for Form 2210).
  5. Withholding counts as paid evenly. Federal tax withheld from wages, pensions or an IRA withdrawal is treated as paid in four equal parts unless you choose otherwise (IRC 6654(g)). A withholding from an IRA late in the year can cover earlier quarters.
  6. States have their own rules. Most states use the same dates. California is different: 30% in April, 40% in June, 0% in September and 30% in January, and if your California AGI is $1,000,000 or more you cannot use the prior-year safe harbor (California FTB, estimated tax payments).

Common questions

Straight answers

How much estimated tax do I pay after selling a property?

Enough that withholding plus payments reach the smaller of 90% of your 2026 tax or 100% of your 2025 tax (110% if your 2025 AGI was over $150,000), spread over the four due dates. The calculator works out both and shows each payment.

When are the 2026 estimated tax payments due?

April 15, 2026, June 15, 2026, September 15, 2026 and January 15, 2027. If a date falls on a weekend or holiday, the next business day counts.

I sold in the fall. Do I owe penalties for April and June?

Not if you use the annualized income installment method on Form 2210 Schedule AI. It ties each payment to income received by the end of each period, so a fall sale is paid for on January 15, 2027.

What is the penalty for paying too little?

It works like interest: the IRS underpayment rate (7% a year for the third and fourth quarters of 2026, set quarterly) on each late amount for the time it is late (IRC 6621, 6654).

Do I still owe more when I file?

Often, yes. The safe harbor stops the penalty, not the tax. If you paid on last year's tax, the rest of this year's tax is due by April 15, 2027. The calculator shows that balance.

Related: Capital gains tax calculator · Home sale capital gains calculator · Rental property capital gains calculator · Net investment income tax calculator · IRMAA calculator · ACA subsidy calculator for a sale year

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Audit trail

Sources and review

Reviewed for the Retirement Literacy Foundation, a 501(c)(3) education nonprofit. Prepared by Hans Goldstein, EA, retirement educator. Admitted to practice before the IRS. Informational only. Not tax, legal or investment advice. Every figure below cites its source so your CPA or attorney can check it.

Figures are 2026 federal amounts unless stated. Examples are illustrative and rounded; your numbers will differ. By , founder, Retirement Literacy Foundation. Last reviewed .

Hans Goldstein is an Enrolled Agent, admitted to practice before the Internal Revenue Service. Not affiliated with or endorsed by the IRS.