IRC Sections 121 and 1031: Current Combined-Use Rules

Start With Property Use

Section 121 concerns gain on a main home. Section 1031 concerns real property held for productive use in a trade or business or for investment. A main home is not eligible for a like-kind exchange merely because the owner wants tax deferral.

When property has genuinely changed between main-home and investment use, both sections may apply if every requirement of both provisions is independently satisfied. This is a CPA- and qualified-intermediary transaction, not a do-it-yourself timing strategy.

Section 121 Baseline

IRS Publication 523 states that the maximum exclusion may be $250,000, or $500,000 for qualifying married joint filers. The general ownership and residence tests require at least 24 months during the five-year period ending on the sale, along with the other eligibility rules.

A home acquired through a like-kind exchange cannot qualify for the Section 121 exclusion if it is sold within five years of acquisition in that exchange.

When Both Sections Apply

IRS Publication 523 states that when the requirements of Sections 121 and 1031 are both met, the Section 121 exclusion is applied first to realized gain and Section 1031 is then applied. Publication 523 directs taxpayers to Revenue Procedure 2005-14 for allocation examples and details.

The replacement property must be held for investment or productive business use. It cannot be converted to a main home immediately after the exchange merely to reach Section 121.

Nonqualified Use

Gain allocable to nonqualified use after 2008 generally is not excludable under Section 121, but the rule has statutory exceptions. IRS Publication 523 specifically excludes certain periods after the last date the property was used as the main home during the five-year lookback, qualified official extended duty, and specified temporary absences. Do not apply a simple “all rental years divided by all ownership years” formula without completing the current IRS worksheet and testing the exceptions.

Depreciation

Section 121 does not exclude the portion of gain equal to depreciation allowed or allowable for business or rental use after May 6, 1997. Do not state a universal tax rate for that gain. Publication 523 describes reporting and recapture rules; the taxpayer's CPA must calculate the actual character, rate, basis adjustment, and reporting forms.

Required File

Before advising on a sale, collect the acquisition and conversion dates, occupancy history, rental records, prior exchange documents, depreciation schedules, adjusted basis, intended replacement property, and proposed closing timeline. Send the file to the taxpayer's CPA and exchange intermediary before contract deadlines are fixed.

Sources

• Internal Revenue Service, Publication 523 (2025), Selling Your Home, fetched and read August 7, 2026.
• Internal Revenue Service, Like-Kind Exchanges - Real Estate Tax Tips, fetched and read August 7, 2026.
• Internal Revenue Service, Revenue Procedure 2005-14, fetched and read August 7, 2026.