Principal Residence Exemption for Unmarried Co-Owners

When unmarried co-owners sell a home, each can claim a capital gains exclusion of up to $250,000 under Section 121 of the tax code—provided each meets the ownership and occupancy tests independently. The rules treat each owner as a separate taxpayer, making the mechanics straightforward but easy to mishandle.

The Basic Rule: $250K Each

The primary residence capital gains exclusion under Section 121 allows a homeowner to exclude up to $250,000 of gain from taxable income when selling a principal residence. For married couples filing jointly, the exclusion doubles to $500,000. For unmarried co-owners, the rule is simpler than many assume: each owner is treated separately.

If Alice and Bob own a house together as unmarried co-owners, and they sell it at a $600,000 total gain, Alice can exclude $250,000 and Bob can exclude $250,000. Their combined exclusion is $500,000—the same as a married couple’s, but structured differently. Each person claims their own exclusion on their own tax return (Form 1040, Schedule D). The IRS does not care that they are unmarried; it cares only that each owner meets the tests individually.

This parity with married couples surprises many. The rules do not penalize unmarried ownership; they reward it—provided both owners qualify.

The Two Tests: Ownership and Occupancy

To claim the exclusion, the homeowner must satisfy two tests, both measured over a five-year look-back window immediately before the sale:

Ownership test: Own the home for at least 2 of the past 5 years. For unmarried co-owners, each person’s ownership fraction (or full ownership if title is joint) counts toward their test. If both are on the deed, both satisfy this test automatically (assuming they held title for 2+ years).

Occupancy test: Live in the home as your primary residence for at least 2 of the past 5 years. This is where unmarried couples often trip. The occupancy test is per owner. If Alice lived in the house the entire 5 years but Bob moved out 18 months before the sale, Bob does not meet the occupancy test. Bob loses his exclusion. Alice keeps hers.

The occupancy does not need to be continuous; it can be fragmented across the five years. Temporary absences (a few weeks’ vacation, a short work assignment) do not disqualify occupancy, provided the home remains the person’s primary residence during that period.

Combining Ownership and Occupancy

Both tests must be satisfied within the same five-year period. This is not “2 years out of the last 5 for ownership” and “2 different years out of the last 5 for occupancy.” Both thresholds refer to the same window.

If Alice owned the home for years 1–5 and lived there for years 1–5, she passes both. If Bob owned it for years 1–5 but lived there for only years 1 and 2, he passes both (he lived there for 2 of the 5 years; the other 3 years he was elsewhere). If Charlie owned it for years 1–3 and lived there for years 1–3, he fails the ownership test (only 3 years of ownership, but needed 2… wait, he passes). Let me clarify: he owned it for 3 years and lived there for 3 years, so he easily passes both.

The common failure case: one co-owner exits the home early (e.g., moves out in year 3) and remains on the deed but living elsewhere for years 3, 4, and 5. If the couple holds and sells in year 6, that co-owner owns the home for all 5 years (passes ownership test) but lived in it for only 2 years (passes occupancy test). So they would still qualify. The rule requires 2 of 5; it does not require the most recent 2 years.

Timing: When Both Tests Must Be Met

A subtlety: both tests must be met within the same 5-year lookback, but they do not need to overlap perfectly. If Alice owned the house years 1–5 and lived in it years 3–5, she still qualifies: she owns it for 5 years and occupies it for 3 years (the 2-year occupancy minimum is met within the 5-year ownership window).

The sale triggers the test. You measure backwards from the sale date. If the home closes on June 15, 2026, the five-year window is June 15, 2021 to June 15, 2026. If an owner lived there for only 1 year and 364 days, they miss the occupancy test by one day.

Partial Exclusion: Life Events and Unforeseen Circumstances

If a co-owner does not meet the full two-year test but faces a qualifying “change in circumstances” (job loss or transfer, health condition, death, divorce, or natural disaster), they may claim a partial exclusion. The exclusion is prorated: $250,000 times the fraction of the required period actually satisfied.

If Bob owned and occupied for 1 year instead of 2, he can exclude $250,000 × (1 year / 2 years) = $125,000, provided the IRS accepts the life-event claim. The rules on what qualifies are strict and fact-specific; “we wanted to sell and move to a cheaper state” typically does not qualify.

How the Gain Is Calculated

For each owner, cost basis usually equals the original purchase price (plus capital improvements, which are added to basis). If Alice and Bob bought a home for $400,000 total and each put in $200,000, Alice’s basis is $200,000 and Bob’s is $200,000. If they sell the home for $1,000,000, the total gain is $600,000. Alice’s gain is $600,000 × 50% = $300,000; Bob’s is $300,000.

Alice excludes $250,000, so her taxable gain is $50,000. Bob excludes $250,000, so his taxable gain is $50,000. Each pays long-term capital gains tax on their $50,000 share.

This calculation assumes equal ownership. If Alice owns 60% and Bob owns 40%, their gains are split 60/40, but each still gets a separate $250,000 exclusion.

Refinancing and Basis Step-up

If Alice and Bob refinance the mortgage, the new loan amount does not affect basis. Basis remains the original purchase price plus improvements. Refinancing is not a taxable event and does not reset the ownership or occupancy clocks.

If one owner dies before the sale, the surviving owner’s basis in their deceased co-owner’s share typically steps up to fair value as of the death date. This can significantly reduce the deceased’s share of the gain (the executor or heir may have zero gain to report). The surviving owner’s exclusion is unaffected.

Common Pitfalls

Occupancy drift: One co-owner moves out and stops living in the home (e.g., moves in with a partner elsewhere) but remains on the deed for financial or administrative reasons. That owner loses the occupancy test and cannot claim the exclusion, even though they still own the property.

Title changes: If title is transferred from one owner to the other shortly before sale (to simplify the transaction), the new owner may not meet the 2-year ownership test. Transfers between unmarried co-owners do not reset the clock, but transfers to a third party do.

Rental periods: If the home is rented out or used as a second home for part of the lookback period, the owner may lose part or all of the exclusion (or face partial exclusion rules). The home must be a principal residence—the place you actually live.

Partial ownership: If one co-owner buys their share from the other mid-ownership, only the buying owner’s holding period counts toward their 2-year test, unless the transfer was a gift or inheritance (which preserves the lookback period). This can be an issue if a couple splits; the exiting partner loses their exclusion eligibility once they no longer own the home.

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