What Is the Section 121 Capital Gains Exclusion?

When you sell your primary residence, the IRS lets you exclude up to $250,000 of capital gains from taxes if you file as single, or up to $500,000 if you file as married filing jointly. This is the Section 121 exclusion — one of the most valuable tax benefits available to homeowners.

To qualify, you must have owned and lived in the home as your primary residence for at least 2 of the 5 years before the sale. You can use this exclusion once every two years. For sellers in Staten Island and Brooklyn, where home values have climbed significantly over the past decade, this exclusion can mean the difference between owing $50,000+ in taxes and owing nothing.

How Capital Gains Tax Works on Home Sales

Your capital gain is calculated as: Sale Price − Selling Costs − Original Purchase Price − Capital Improvements = Gain. If you qualify for the Section 121 exclusion, that amount is subtracted from your gain. Any remaining taxable gain is taxed at federal long-term capital gains rates (0%, 15%, or 20% depending on your income) plus the 3.8% Net Investment Income Tax (NIIT) if your income exceeds $200,000 (single) or $250,000 (married). New York State also taxes capital gains as ordinary income at rates from 4% to 10.9%.

If you owned the property for less than one year, gains are taxed as ordinary income at your marginal tax rate — which can be significantly higher than long-term capital gains rates.

How to Use This Calculator

Enter your original purchase price and any capital improvements you made (renovations, additions, new roof — not routine maintenance). Then enter your sale price and estimated selling costs (broker commissions, transfer taxes, attorney fees). Select your filing status, whether the home qualifies as your primary residence, your approximate income, and how long you owned it. The calculator computes your adjusted cost basis, total gain, Section 121 exclusion (if eligible), and estimates your federal and NYS tax liability.

Example 1: Staten Island Homeowner Sells After 10 Years

A married couple bought their home in Dongan Hills for $450,000 in 2015. They spent $60,000 on a kitchen renovation and bathroom remodel. They sell in 2025 for $750,000 with $48,000 in selling costs. Their adjusted basis is $510,000 ($450K + $60K). Net proceeds are $702,000 ($750K − $48K). Capital gain: $192,000. Since this is below the $500,000 married exclusion, they owe $0 in capital gains tax.

Example 2: Brooklyn Brownstone Sale with Taxable Gain

A single owner purchased a brownstone in Bay Ridge for $400,000 in 2012, invested $80,000 in improvements, and sells for $1,100,000 with $72,000 in selling costs. Adjusted basis: $480,000. Net sale: $1,028,000. Capital gain: $548,000. After the $250,000 single exclusion, taxable gain is $298,000. At the 15% federal rate plus 3.8% NIIT plus approximately 6.85% NYS, total estimated tax is approximately $76,000. Still a massive profit — but proper planning could have reduced the bill further.

Example 3: Investment Property with No Exclusion

An investor sells a 2-family property in Tottenville, Staten Island. Purchased for $550,000, no improvements, sold for $800,000 with $52,000 in selling costs. Capital gain: $198,000. Because this was never a primary residence, there is no Section 121 exclusion. At 15% federal + 3.8% NIIT + 6.85% NYS, the estimated tax bill is approximately $50,800. Strategies like a 1031 exchange could defer this entirely.

Frequently Asked Questions

Disclaimer: This calculator provides estimates for educational purposes only. It is not tax advice. Capital gains tax calculations depend on your complete financial situation, filing status, deductions, and applicable exemptions. Consult a qualified CPA or tax attorney before making decisions based on these estimates. Joseph Ranola | Bridge & Boro Real Estate Team | Exp Realty | (917) 905-2541