Do I Pay Capital Gains Tax When I Sell My Home in NYC? The Section 121 Math

Most of the Staten Island and Brooklyn homeowners I work with have owned their homes for 10+ years, often 20 or 30. When they go to sell, they’re sitting on $300,000 to $700,000 in unrealized gains. The federal Section 121 exclusion is what determines whether they pay zero capital gains tax or six figures of tax. Most sellers don’t know the rules. Many disqualify themselves accidentally.

The Basic Rule

If you’ve owned the home for at least 2 of the past 5 years and used it as your primary residence for at least 2 of the past 5 years, you can exclude up to $250,000 of gain (single filer) or $500,000 of gain (married filing jointly) from federal capital gains tax. The two periods don’t have to overlap. The exclusion is per-sale, not per-lifetime - but you can only use it once every 2 years.

How Gain is Calculated

Gain = Sale price − selling costs − adjusted basis. Selling costs include commission, transfer taxes, attorney, and most title fees - all of which our seller net proceeds calculator accounts for. Adjusted basis = original purchase price + capital improvements − any depreciation taken. Capital improvements (new roof, kitchen renovation, central air, finished basement) increase your basis and reduce taxable gain. Keep receipts. This is the single most overlooked area in NYC home sales.

The Four Most Common Pitfalls

• Renting out the home. If you rent the property in the 5 years before sale, you may have to recapture depreciation and lose part of the exclusion.
• Selling within 2 years of a previous Section 121 use. The exclusion is once every 2 years. Sell two homes back-to-back and only the first qualifies.
• Co-owners not all qualifying. If a parent is on title for estate planning but doesn’t live there, only your share of the gain qualifies for exclusion.
• Forgetting capital improvements. Every dollar of qualified improvement raises basis and reduces taxable gain. Sellers routinely leave $50,000+ of basis on the table by not tracking renovations over the years.

NY State Tax Still Applies

Section 121 is a federal exclusion only. NY State capital gains tax (which is taxed as ordinary income, currently up to ~10.9 percent for high earners) still applies to any portion of the gain that would otherwise be taxable. For most NYC homeowners under the federal exclusion threshold, the state tax bill is small - but it’s not zero, and your accountant should account for it.

What This Calculator Does

Run your purchase price, year of purchase, capital improvements, and projected sale price. The calculator tells you your projected gain, your Section 121 exclusion, your federal taxable gain, and a rough state tax estimate. It’s not a substitute for your CPA - but it tells you within 5 minutes whether you have a Section 121 problem worth talking to your CPA about.

Selling a long-held home in Staten Island or Brooklyn? Book a 20-minute consultation and I’ll bring a CPA-friendly net sheet to the conversation.