Updated June 17, 2026
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IRS rules give you exactly 45 calendar days from your relinquished property closing to identify replacement properties in writing, and 180 calendar days from that same closing date to complete the purchase. Both deadlines are absolute. No extensions are granted for financing problems, slow sellers, or cold feet. The only recognized exception is a presidentially-declared federal disaster affecting the exchange area.
The 45-day identification deadline
The clock starts the day after your relinquished property closes. By midnight on day 45, you must deliver a written identification of potential replacement properties to your qualified intermediary, the seller, or another party to the exchange. The IRS does not accept late filings. A phone call to your QI naming a property does not count; the identification must be in writing.
You have three identification rules to choose from:
- Three-property rule: identify up to three properties of any value. This is the most common approach.
- 200% rule: identify any number of properties as long as their combined fair market value does not exceed 200% of the relinquished property's sale price.
- 95% rule: identify any number of properties at any value, but you must acquire at least 95% of the total identified value. This is almost never used in practice because it is nearly impossible to satisfy.
Once submitted, you are locked in. Substitutions are allowed only under the 95% rule, or if an identified property is destroyed, condemned, or otherwise becomes unavailable through no fault of yours. Buyer's remorse does not qualify.
The 180-day closing deadline
You must close on the replacement property by the earlier of 180 calendar days from the relinquished closing, or the federal tax return due date for the year of the sale, including any filing extensions. That second condition is the one that catches people. Sell in November and the April return deadline arrives inside the 180-day window. File for a tax return extension and you preserve the full 180 days.
How to calculate your deadlines
Count from the day after the relinquished deed transfers, or after escrow closes in escrow states. Use the timeline calculator to get your exact dates. Missing day 45 by one day disqualifies the identification; missing day 180 by one day disqualifies the exchange. There is no partial credit.
Common timeline mistakes
The most common mistakes: identifying only one property that then falls through, failing to file a tax return extension on a late-year sale, and submitting a written identification that is too vague to satisfy the QI. Naming two or three properties under the three-property rule costs nothing at day 45 and can save the entire exchange at day 60.
This article is for educational purposes only and is not tax or legal advice. Deadlines and rules are current as of the date above and may change. Consult a qualified intermediary and tax professional before structuring any exchange.
See exactly what you would defer
Enter your sale price, adjusted basis, and mortgage payoff to see deferred gain, any taxable boot, and cash available for the replacement.