A 1031 exchange defers capital gains tax by rolling proceeds from one investment property into another. Two deadlines govern it and neither is extendable: 45 days to identify replacement property, and 180 days to close. Miss either and the exchange fails and the whole gain becomes taxable in that year.
The two clocks that decide everything
Both periods start on the day you transfer the relinquished property, and they run concurrently rather than sequentially — the 45 days are the first 45 of the 180.
- ·45-day identification period. You must identify replacement property in writing within 45 days of the sale closing.
- ·180-day exchange period. You must receive the replacement property within 180 days of the sale — or by the due date of your tax return for that year including extensions, whichever is earlier. That second condition catches people whose sale falls late in the calendar year, because the return deadline can arrive well before day 180.
Both are stated by the IRS and neither bends for a failed inspection, a financing delay or a seller who walks. That is why identifying more than one candidate property within the 45 days is standard practice rather than indecision.
What actually qualifies now
The scope of Section 1031 narrowed considerably. Since January 1, 2018 it applies only to real property held for productive use in a trade or business or for investment. Exchanges of personal property, equipment, vehicles and intangibles no longer qualify at all.
Two further limits matter in practice. Property held primarily for sale — a flip, or a developer's inventory — does not qualify, because it is not held for investment. And a personal residence does not qualify; that is the domain of the Section 121 exclusion, which is a different provision with different rules. Our cost to sell calculator handles the primary-residence case.
"Like-kind" is broad within real property: an apartment building can be exchanged for raw land, a retail unit for a warehouse. The constraint is the character of the holding, not the type of building.
What this calculator does not tell you
- ·Deferral is not forgiveness. The deferred gain carries into the replacement property's basis. Sell that without another exchange and the whole accumulated gain becomes taxable.
- ·Boot. Cash or debt relief received in the exchange is taxable to that extent, even if the rest qualifies.
- ·The qualified intermediary is mandatory. You cannot take receipt of the proceeds. Touching the money ends the exchange.
- ·State treatment varies. Some states impose their own rules and clawbacks on exchanges out of state. This calculator models federal deferral only.
Reporting is its own step: a completed exchange is declared on Form 8824 for the year the relinquished property was transferred, which is how the deferred gain and the adjusted basis of the replacement property are established on the record. An exchange that is executed correctly but never reported is not a deferral.
This is one of the few areas of property tax where the deadlines are absolute and the penalty for a technical failure is the entire tax bill. Treat the output here as a sizing tool and engage a qualified intermediary before the relinquished property closes, not after.
Methodology
Deferral is computed from the gain you enter and the structure of the exchange. The 45-day identification and 180-day exchange periods, and the post-2017 restriction of Section 1031 to real property held for business or investment, are quoted from the IRS pages listed below. This calculator models federal deferral and does not model boot, depreciation recapture rates, or state-level rules.
Sources
- IRS — Like-Kind Exchanges, Real Estate Tax Tips — accessed 2026-09-05
- IRS — Instructions for Form 8824, Like-Kind Exchanges — accessed 2026-09-05