In short
Day 0, day 45, day 180 and the return due date: every 1031 deadline, who it is sent to, what can move it, and the two dates after closing that still matter.
A deferred exchange has four dates: the day you transfer the relinquished property, the 45th day after it, the 180th day after it, and the due date of your tax return for that year. Everything else, from identification letters to disaster relief, hangs on those four. This page lists each one, the rule behind it, and the detail that most often catches sellers. Print it and keep it with your exchange agreement.
Day 0: the clock starts at the transfer
The periods run from “the date the taxpayer transfers the relinquished property,” which in practice is the closing date of your sale (Reg. section 1.1031(k)-1(b)(2)). There is no grace for a late recording, a delayed wire or a buyer who moves in early; the day of the transfer is day 0 and the next day is day 1. If you sell more than one property in the same exchange, the periods run from the earliest transfer. Make sure your exchange agreement is signed and the intermediary is in the chain before that closing, not after.
Day 45: identification, in writing, to the right person
The identification period “ends at midnight on the 45th day” after the transfer. The regulation counts days, not business days, and says nothing about weekends or holidays, so a day 45 that lands on a Sunday is still day 45. Our page on weekend and holiday deadlines explains the practical consequence.
Under paragraph (c)(2), the identification must be a written document signed by you and “hand delivered, mailed, telecopied, or otherwise sent” before the period ends, either to the person obligated to transfer the replacement property or to any other person involved in the exchange who is not you or a disqualified person. Your intermediary is the usual recipient. Under (c)(3), each property must be unambiguously described: a legal description, street address or distinguishable name for real property.
Three limits apply under (c)(4): up to three properties of any value; or any number of properties whose total fair market value does not exceed 200 percent of what you sold; or, if you overshoot both, you must actually acquire at least 95 percent of the value you identified. Identify more than the rules allow and (c)(4)(iii) treats you as having identified nothing. Two escape hatches: any property you actually receive before day 45 counts as identified, and under (c)(6) you may revoke an identification in a signed writing any time before day 45. See how many properties can be identified.
Day 180, or your return due date, whichever comes first
The exchange period “ends at midnight on the earlier of the 180th day thereafter or the due date (including extensions) for the taxpayer’s return” for the year of the transfer (Reg. section 1.1031(k)-1(b)(2)(ii); section 1031(a)(3)). The replacement property must be received, meaning title transferred, by then. Contract signed but not closed does not count.
The due-date rule is the one that surprises late-year sellers. A hypothetical makes it concrete. Sell on October 15, 2026: day 45 is November 29, 2026 and day 180 is April 13, 2027, two days before an April 15 due date, so the full 180 days are available. Sell on November 15, 2026: day 45 is December 30, 2026, but day 180 is May 14, 2027, after the due date. Unless you file an extension for your 2026 return, your exchange period ends April 15, 2027. The Form 8824 instructions state the rule the same way. Check the dates against your own calendar and your CPA’s filing plan; our tax year straddle guide covers the reporting side.
Two things that move the dates
Federally declared disasters. Section 17 of Rev. Proc. 2018-58 postpones a day 45 or day 180 deadline that falls on or after the disaster date “by 120 days or to the last day of the general disaster extension period” announced by the IRS, whichever is later, but never beyond the due date of your return (including extensions) or one year. You qualify if you transferred the relinquished property on or before the disaster date and you are an affected taxpayer, or you have difficulty meeting the deadline because the relinquished or replacement property is in the covered disaster area, among other listed reasons. The relief applies only when the IRS news release for that disaster provides it. Nothing else extends the periods; see can the 45 or 180 days be extended.
Reverse exchanges. If you must buy before you sell, Rev. Proc. 2000-37 lets an accommodation titleholder hold the property under a qualified exchange accommodation arrangement. The IRS summary is that the property “is parked for no more than 180 days” (Fact Sheet FS-2008-18); the disaster relief above also reaches the deadlines in that procedure. The reverse exchange guide lays out the steps.
After closing: two dates that still matter
The return for the year of the transfer. You must file Form 8824 with that return, even if the replacement closed the following year. If the exchange crosses a year-end and then fails, Reg. section 1.1031(k)-1(j)(2) can treat the proceeds as received when the intermediary actually pays them, which may put the gain in the second year.
Two years after the last transfer. If you exchanged with a related party, section 1031(f) undoes the deferral if either of you disposes of the property received within two years, with limited exceptions, and the Form 8824 instructions require the form to be filed for the two following years.
What to do now
- Write day 0, day 45, day 180 and your return due date on one sheet the day your sale contract is signed, and give a copy to your intermediary and CPA.
- Decide before day 45 whether a DST will be on your list as the third name; our page on identifying a backup DST explains why.
- If day 180 falls after your filing deadline, put the extension on your CPA’s calendar now.
- If a disaster is declared in your county or the replacement property’s county, read the IRS release for that disaster and recompute both dates. Start your exchange plan with the sheet in hand.
