How to Pay Estimated Taxes on Capital Gains: Safe Harbor Rules

If you sold stock, a rental property, or another investment at a profit, the IRS expects you to pay federal tax on that gain during the year rather than waiting until you file. To pay estimated taxes on capital gains, figure the federal tax the gain will add to your return (including the 3.8% net investment income surtax if it applies), then send that amount to the IRS by the quarterly deadline for the period in which the sale closed. You generally have to do this if you expect to owe at least $1,000 after withholding and refundable credits.¹ Getting the amount and timing right matters, because the underpayment interest rate has been running at 7%.²

Do You Actually Owe an Estimated Payment

Two conditions have to be true before the IRS requires quarterly payments: you expect to owe at least $1,000 for the year after withholding and refundable credits, and you expect your withholding and credits to be less than the smaller of 90% of this year’s tax or 100% of last year’s. If your prior-year adjusted gross income was over $150,000 ($75,000 if married filing separately), that 100% figure becomes 110%.³

A single stock sale or real estate closing can push you past $1,000 even when your paycheck withholding perfectly covers your salary. That’s the situation most employees find themselves in after their first big gain.

Figure the Tax on the Gain

Your rate depends on how long you held the asset. If you held it a year or less, the profit is a short-term gain, taxed at the same rates as your wages. The gain stacks on top of your other income, so its marginal rate depends on your total taxable income for the year.⁴

Assets held longer than a year qualify for long-term rates. Most investors pay 15%. Taxable income up to $49,450 single or $98,900 married filing jointly falls in the 0% bracket for 2026; the 20% rate kicks in above $545,500 single or $613,700 married filing jointly.⁴ The gain itself counts toward taxable income, so a large sale can push part of itself into the next bracket.

Two categories of long-term gains use different maximum rates. Collectibles (coins, art, antiques, precious metals) top out at 28%. When you sell depreciable real estate at a profit, the part of the gain matching depreciation you previously claimed, called unrecaptured Section 1250 gain, is taxed at up to 25%.⁵ For a rental you’ve depreciated for years, the recapture piece alone can be a substantial share of the estimated payment.

Add the 3.8% Surtax if It Applies

The Net Investment Income Tax adds 3.8% on top of the regular capital gains tax for higher earners. It applies to the lesser of your net investment income or the amount by which your modified AGI exceeds $200,000 single, $250,000 married filing jointly, or $125,000 married filing separately.⁶ These thresholds don’t adjust for inflation. Include the surtax in your estimated payment when your income clears them.

Reduce the Gain Before You Calculate

Losses come off first. Net short-term gains against short-term losses and long-term against long-term, then combine. If losses exceed gains, up to $3,000 of the net loss ($1,500 if married filing separately) offsets ordinary income, and any remainder carries forward.⁵

Selling losers to offset a gain is legitimate, but the wash sale rule disallows the loss if you buy the same or a substantially identical security within 30 days before or after the sale.⁷ The disallowed amount attaches to the basis of the replacement, so it isn’t gone forever, but it doesn’t help this year’s estimated tax. The rule reaches across your accounts, including IRAs and your spouse’s accounts.

If the gain came from selling your home, check the exclusion before sending any payment. Federal law excludes up to $250,000 of gain on a principal residence for single filers, or $500,000 for married couples filing jointly, when you owned and lived in the home for at least two of the five years before the sale.⁸ Only gain above the exclusion is taxable. A single filer who bought at $300,000 and sold at $500,000 with the ownership and use tests met owes nothing on that sale.

Match the Payment to the Right Quarter

Federal estimated taxes are due four times a year, and each installment covers a specific slice of the calendar:⁹

April 15, for income from January 1 through March 31.
June 15, for income from April 1 through May 31.
September 15, for income from June 1 through August 31.
January 15 of the following year, for income from September 1 through December 31.

When a deadline falls on a weekend or federal holiday, it moves to the next business day. Pay the tax on a gain by the deadline for the period when the sale closed. Sell on July 20, and the payment is due September 15.

Late-Year Gains: The Annualized Income Method

The default approach splits your yearly tax into four equal payments. That’s fine when income arrives evenly, but a stock sale in October shouldn’t retroactively trigger payments back in April and June. The annualized income installment method lets you calculate what was owed based on income actually received through each quarterly cutoff, producing smaller payments early in the year and a larger one in the quarter the gain hit.¹⁰ You lock this in by filing Schedule AI with Form 2210 attached to your annual return; without it, the IRS treats your uneven payments as late.¹¹

Or Increase Your Paycheck Withholding

If you have a W-2 job, there’s a shortcut that many people miss. File a new Form W-4 with your employer and either report the expected non-wage income on Step 4(a) or ask for a flat additional amount on Step 4(c).¹² The IRS treats withholding as paid evenly across the year no matter when it’s actually taken, so a big boost to withholding late in the year covers earlier quarters too. This is often the cleanest fix after a late-year gain when the earlier estimated deadlines have already passed. Reset the W-4 after year-end so you don’t overwithhold next year.

Send the Payment

The IRS worksheet in Form 1040-ES walks through the arithmetic if you want to check yourself.¹³ Once you know the amount, you have several ways to submit it:

IRS Direct Pay pulls funds straight from a checking or savings account, no enrollment, and you select “Estimated Tax” and the tax year.
EFTPS, the Treasury Department’s free system, schedules payments up to 365 days ahead. Enrollment takes about a week, so sign up before you need it.¹⁴
Credit or debit card, through an IRS-authorized processor, with a convenience fee (around 2% for credit, flat for debit).
Check or money order, mailed with a Form 1040-ES voucher to the address for your state, payable to “United States Treasury,” with your Social Security number and the tax year in the memo line.¹³

Electronic payments post in a day or two. Mailed payments have to be postmarked by the deadline, so leave a buffer.

Lock In No Penalty With the Prior-Year Safe Harbor

The underpayment penalty is calculated as interest on each quarter’s shortfall for the time it went unpaid, at 7% for the first quarter of 2026, with quarterly adjustments.² A quarter’s shortfall accrues its own interest even if you overpay the next quarter.

The cleanest way to guarantee no penalty when a gain is unpredictable is the prior-year safe harbor. Pay at least 100% of last year’s total tax (110% if last year’s AGI was above $150,000) through a combination of withholding and estimated payments, and the IRS can’t assess an underpayment penalty regardless of how much this year’s tax turns out to be.³ If your 2025 tax was $30,000 and your AGI cleared $150,000, paying $33,000 across 2026 through withholding and estimates keeps you penalty-free, even if a big gain makes your actual 2026 tax $80,000. You’ll owe the balance at filing, but without a penalty on top.

The alternative safe harbor, paying at least 90% of this year’s tax, works when you can forecast income accurately. A surprise gain often breaks that calculation, which is why the prior-year number, fixed and knowable on January 1, is the one most investors with volatile income should aim for.

State Taxes Are Separate

Federal estimated payments cover only your federal liability. Most states tax capital gains as ordinary income, with top rates from roughly 5% to over 13%; nine states don’t tax the income at all. Where your state taxes gains, you’ll calculate and submit state estimated payments on your state’s own schedule.

At Filing Time

Paying quarterly doesn’t replace reporting each sale on your return. Most transactions go on Form 8949 with purchase date, sale date, proceeds, and cost basis, then flow to Schedule D.¹⁵ Your brokerage supplies most of it on Form 1099-B. When the 1099-B shows basis was reported to the IRS and no adjustments are needed, some transactions can be summarized directly on Schedule D.

If you used the annualized income method to justify lower payments in earlier quarters, attach Form 2210 with Schedule AI. Without it, the IRS will compute the penalty as though equal payments were owed every quarter.¹⁰ Keep records of each sale date and each payment date; the timing drives both the annualized calculation and any penalty math.

1
Internal Revenue Service. Estimated Taxes
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Internal Revenue Service. Rev. Rul. 2025-22 – Determination of Rate of Interest
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Internal Revenue Service. How Do I Know if I Have to Make Quarterly Individual Estimated Tax Payments?
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Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026
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Internal Revenue Service. Topic No. 409, Capital Gains and Losses
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Internal Revenue Service. Net Investment Income Tax
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Office of the Law Revision Counsel. 26 U.S. Code 1091 – Loss from Wash Sales of Stock or Securities
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Office of the Law Revision Counsel. 26 USC 121 – Exclusion of Gain from Sale of Principal Residence
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Internal Revenue Service. Estimated Tax – Frequently Asked Questions
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Internal Revenue Service. Instructions for Form 2210 – Schedule AI, Annualized Income Installment Method
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Internal Revenue Service. Underpayment of Estimated Tax by Individuals, Estates, and Trusts
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Internal Revenue Service. Tax Withholding – How to Get It Right
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Internal Revenue Service. Form 1040-ES – Estimated Tax for Individuals
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Internal Revenue Service. EFTPS – The Electronic Federal Tax Payment System
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Internal Revenue Service. Instructions for Form 8949