Capital Gains Tax Calculator for Married Couples (2026)

Enter your combined ordinary income and capital gains to see your 2026 LTCG rate, NIIT exposure, and how much additional gains you could realize tax-free this year.

How the 0% capital gains bracket works for married couples

The IRS taxes long-term capital gains at a preferential rate — 0%, 15%, or 20% — depending on your total taxable income. For 2026, married couples filing jointly pay 0% on long-term gains when their total taxable income stays at or below $98,900.¹

That's a remarkable benefit. A couple selling $80,000 worth of appreciated stock — a position they've held for three years — could pay literally nothing in federal capital gains tax if their combined taxable income is modest enough. Early retirees, couples in a low-income transition year, and couples doing Roth conversions often engineer their income specifically to maximize this 0% window.

The stacking rule: ordinary income fills brackets first

This is the detail that most online calculators get wrong. Capital gains don't sit in their own separate bucket — they are stacked on top of your ordinary taxable income when determining which LTCG rate applies. Here's how it works:

1. Start with your combined ordinary income (wages, self-employment, short-term gains, Social Security, pension income, etc.).
2. Subtract the standard deduction ($32,200 for MFJ in 2026) to get ordinary taxable income.
3. Your long-term capital gains sit on top of ordinary taxable income.
4. LTCG is taxed at 0% until the combined total reaches $98,900; at 15% until $613,700; at 20% above that.

Example: A couple has $80,000 in wages and $60,000 in LTCG from selling index funds. Ordinary taxable income = $80,000 − $32,200 = $47,800. The 0% bucket holds $98,900 − $47,800 = $51,100 of space. Their $60,000 of LTCG fills $51,100 at 0% and the remaining $8,900 at 15%. Total LTCG tax: $8,900 × 15% = $1,335 — on a $60,000 gain. If they had sold $9,000 less, the entire gain would have been tax-free.

2026 LTCG tax brackets — married filing jointly

Short-term capital gains (assets held 1 year or less) are taxed as ordinary income at your regular marginal bracket — 10% through 37% — not at these preferential rates.

Net Investment Income Tax (NIIT) — the 3.8% surcharge

On top of the LTCG rates above, a 3.8% NIIT applies to net investment income when your Modified Adjusted Gross Income (MAGI) exceeds $250,000 for married couples filing jointly.² Unlike the income tax brackets, the NIIT thresholds are not indexed for inflation — they've been frozen at $250,000 (MFJ) and $200,000 (single) since 2013. This means more couples cross the NIIT threshold each year as nominal incomes rise.

The NIIT base is the lesser of: (a) your net investment income, or (b) the amount by which your MAGI exceeds the threshold. So if your MAGI is $280,000 and your LTCG is $100,000, the NIIT base is min($100,000, $30,000) = $30,000, and NIIT = $30,000 × 3.8% = $1,140.

Importantly, a couple in the 15% LTCG bracket whose MAGI crosses $250,000 pays 15% + 3.8% = 18.8% on gains above the threshold — not 15%. High-income couples doing tax-loss harvesting or managing capital gain realization often target staying just below the $250,000 MAGI NIIT floor as a planning priority.

Tax strategies for married couples with capital gains

0% bracket harvesting. If your combined taxable income will be below $98,900 this year — a Roth conversion year, an early retirement year, a sabbatical, a year with large deductions — consider deliberately selling appreciated positions to realize gains at 0%. You reset your cost basis at a higher level, reducing future taxable gains. This is particularly powerful in years before Required Minimum Distributions begin (pre-RMD Roth conversion window).

Asset location. Hold tax-inefficient assets (REITs, high-yield bonds, actively-managed funds with high turnover) in tax-deferred accounts (401k, IRA). Hold tax-efficient assets (broad index funds, growth stocks held long-term) in taxable brokerage accounts where LTCG rates apply. A couple with four accounts (2× 401k, 1× taxable) has meaningful location choices that compound for decades.

Tax-loss harvesting. Capital losses in a taxable account offset capital gains dollar-for-dollar. Losses above gains can offset up to $3,000 of ordinary income per year and carry forward indefinitely. For married couples managing a joint taxable account, the wash sale rule applies household-wide — you can't sell at a loss in one spouse's account and buy the identical security in the other spouse's account within 30 days.³

Installment sales. Selling a business or real estate? Structuring as an installment sale spreads LTCG recognition across multiple years, potentially keeping each year's gain in the 0% or 15% bracket rather than bunching into a single high-rate year.

Qualified Opportunity Zone (QOZ) investments. Capital gains invested in a QOZ fund within 180 days defer taxation on the original gain and — if held 10+ years — permanently exclude gains on the QOZ investment itself. Useful for very large single-year gain events.

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