Suppose you bought a house in 1998 for $150,000 and you could sell it this spring for $600,000. On paper that is a $450,000 gain, and a reasonable person might assume a painful tax bill is coming. For most homeowners in that position, the actual taxable amount is far smaller, and for many it is zero. The reason is one of the most valuable provisions in the tax code for ordinary families: the home sale exclusion under Section 121, explained by the IRS in Tax Topic 701.
The rule lets you exclude up to $250,000 of gain from the sale of your main home if you file single, and up to $500,000 if you are married filing jointly. But the exclusion has tests, the math starts somewhere other than your purchase price, and a few common situations (rentals, home offices, recent moves) can shrink it. Here is how it actually works in 2026.
The two tests you have to pass
To claim the full exclusion, you must meet both an ownership test and a use test. During the five years ending on the date of sale, you need to have owned the home for at least two years and lived in it as your main home for at least two years. The two years do not have to be continuous, and for married couples only one spouse needs to pass the ownership test, though both must pass the use test to claim the full $500,000.
There is also a frequency limit: generally you cannot use the exclusion if you already excluded gain from another home sale in the two years before this one. The full details, including worksheets, are in IRS Publication 523, Selling Your Home.
Your gain is smaller than you think
The taxable gain is not the sale price minus what you paid. It is the “amount realized” minus your “adjusted basis,” and both adjustments work in your favor.
The amount realized is the sale price minus selling expenses: the real estate commission, legal fees, and transfer taxes all come off the top. Your adjusted basis starts with what you paid, plus many of your original closing costs, plus the cost of capital improvements over the years. A new roof, a remodeled kitchen, a deck, a furnace, central air: all of it adds to basis. Repairs and routine maintenance do not count, but improvements with a useful life beyond a year generally do. Publication 523 has the dividing line.
Take the example above. If that 1998 buyer paid a 5 percent commission ($30,000) and put $60,000 of documented improvements into the house over 28 years, the gain is not $450,000. It is $600,000 minus $30,000 minus a $210,000 adjusted basis, or $360,000. A married couple filing jointly excludes all of it. A single filer excludes $250,000 and reports $110,000.
This is why keeping receipts for improvements matters, even decades later. Every documented dollar of basis is a dollar that never shows up on your return.
What you owe on gain above the limit
Gain above the exclusion is a long-term capital gain if you owned the home more than a year, taxed at 0, 15, or 20 percent depending on your taxable income, as laid out in IRS Tax Topic 409. Higher-income sellers may also owe the 3.8 percent net investment income tax, which applies when modified adjusted gross income exceeds $200,000 for single filers or $250,000 for joint filers. Note that a big home sale can push your income over those thresholds in the year of sale even if you never come close in a normal year.
Moved early? You may get a partial exclusion
If you sold before hitting the two-year marks because of a work-related move, a health condition, or certain unforeseeable events (a death in the household, divorce, multiple births from one pregnancy, and similar circumstances listed in Publication 523), you can claim a reduced exclusion. It is prorated by time: live there 12 months of the required 24 and a single filer’s cap becomes $125,000 rather than $250,000. For most people forced to move early, that still wipes out the entire gain.
Situations that complicate the math
Widowed sellers. A surviving spouse who has not remarried can generally still use the full $500,000 exclusion if the home is sold within two years of the spouse’s death and the couple met the tests before the death.
Rental use and home offices. If you rented the home out or claimed depreciation for a home office, the depreciation you took (or could have taken) after May 6, 1997 cannot be excluded; it is recaptured at a rate of up to 25 percent. Stretches when the home was not your main residence after 2008 can also make part of the gain ineligible under the “nonqualified use” rules.
Military and certain federal service. Service members on qualified official extended duty can suspend the five-year test period for up to ten years, a significant break for families who move on orders.
The paperwork question
If your entire gain is excludable and you did not receive a Form 1099-S from the closing agent, you generally do not need to report the sale at all. If you did receive a 1099-S, report the sale on Form 8949 and Schedule D even when the exclusion zeroes out the tax; the IRS computers will be looking for the sale, and reporting it with the exclusion applied heads off a mismatch notice.
One last piece of perspective. The $250,000 and $500,000 caps were set by Congress in 1997 and are not indexed for inflation, so each year more long-tenured homeowners in expensive markets find their gains brushing the limit. If you have owned your home for decades, an afternoon reconstructing your improvement history could be worth real money at closing time.
This article was produced with AI assistance and reviewed by a human editor. Figures are linked to their primary sources; where a claim could not be verified from the public record, we say so.
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