The short answer
They overlap: the 45 days are the first 45 days of the 180, and there is no version of a 1031 exchange that runs 225 days. Both periods are measured from the same event, the transfer of the property you sold, so a notice delivered on day 45 leaves 135 days to take title to everything on it. Section 1031(a)(3) counts the 180 days from that transfer, closing to closing, and identifying early buys you nothing extra. The only thing that makes the window shorter than 180 days is your own tax filing deadline.
At a glance
| Both periods begin | On the date you transfer the property you sold, not on two different dates |
|---|---|
| Identification ends | Midnight on day 45 |
| Exchange ends | Midnight on day 180, or your return due date with extensions if that is earlier |
| Days left after day 45 | 135, and that is the number your lender and escrow officer need |
| How 180 is measured | Closing to closing; purchase contracts and offers do not start it |
| Maximum | 180 days; a reverse exchange is capped at 180 combined days, not stacked on top |
| Hypothetical | Close June 15, 2026 → identify by July 30 → close by December 12, 2026 |
One event starts both periods, which is why they cannot be added together
The statute hangs both limits on the same date. Section 1031(a)(3) treats property as not like-kind if it "is not identified ... on or before the day which is 45 days after the date on which the taxpayer transfers the property relinquished in the exchange," or if it "is received after ... the day which is 180 days after" that same transfer.
Read together, those are one timeline with a checkpoint at day 45, not two timelines laid end to end. The idea that identifying on day 45 restarts a fresh 180 days comes from misreading the second limit as running from the identification instead of from the sale.
Qualified intermediaries describe it the same way. IPX1031 measures both periods from the transfer of the first relinquished property, and no safe harbor anywhere in the regulations produces a 225-day exchange.
Day 46 to day 180 is 135 days, and that is the window your financing has to fit
Subtract and the practical number appears: 135 days between the identification notice and the last possible closing. That is the period in which appraisals get ordered, loan committees meet, title objections get cured and estoppels come back from tenants.
It is also less generous than it sounds, because almost nobody sends the notice on day 45 and then starts work. Due diligence on the named properties has usually been running since week two, and a purchase contract signed around day 50 leaves roughly four months of runway.
Plan the last closing for day 160 to day 170 rather than day 180. A lender that slips past the deadline does not get you more time.
Two dates belong in the replacement purchase contract itself: an outside closing date that lands before day 180, and the right to close sooner if the loan clears early. Sellers who know you are on a 1031 clock will price the certainty, so ask for the early-close right before you disclose the deadline.
Closing to closing, not contract to contract
The count ends when you receive the replacement property, not when you agree to buy it. A contract signed on day 120 with a closing scheduled for day 195 is a failed exchange with a signature on it.
The same applies at the front: the 180 days does not start when you list the property, sign the sale contract or open escrow. It starts when the sale closes, which is the date the benefits and burdens of ownership passed to your buyer.
One more counting trap: 180 days is not six months. A closing on Monday June 15, 2026 reaches day 180 on Saturday December 12, 2026, three days before the date most people would have written on the calendar.
Buying inside the first 45 days is allowed, and the closing doubles as the identification
Nothing requires you to wait. If the replacement is ready, you can close it on day 12 and the exchange is complete on day 12.
The regulation then does the paperwork for you: "any replacement property that is received by the taxpayer before the end of the identification period will in all events be treated as identified before the end of the identification period." That rule, and when you still want a written notice anyway, is covered separately.
What an early closing does not do is reopen anything. Once every property you identified has been received, the exchange is over and the intermediary's remaining balance is yours.
One consequence catches people out. Closing your only replacement on day 20 with money left over does not give you until day 45 to find somewhere to put the rest, because the exchange ends when the last identified property is received and the balance comes back as boot.
Two things make the window shorter than 180 days
The first is your tax return. Section 1031(a)(3)(B)(ii) ends the period at "the due date (determined with regard to extension)" of the return for the year of the sale, so a 2026 sale closing after October 17, 2026 runs out on April 15, 2027 rather than on day 180 unless an extension is filed first.
The second is a second sale. If two properties go into one exchange on different dates, both periods run from the earlier closing, so the later sale effectively gets less than 180 days.
Neither of these lengthens anything. Only federally declared disaster relief can move either date, and your CPA or attorney should confirm the count against your closing documents before you build a schedule on it.
- Individual, 2026 sale closing on or before October 17, 2026: the full 180 days is available without filing anything.
- Individual, 2026 sale closing after October 17, 2026: Form 4868 is what preserves the remaining days.
- Calendar-year partnership or S corporation selling after September 16, 2026: Form 7004, because the return is due March 15, 2027.
- Two relinquished closings in one exchange: count from the first one, not from the one that worries you.
- Reverse exchange: the 180 days covers the whole parking arrangement, so it is a ceiling and not an extension.
A hypothetical calendar for a June 15, 2026 closing
Working the dates backwards from day 180 is the difference between a comfortable exchange and a rushed one.
- Monday June 15, 2026: sale closes, proceeds go to the intermediary, day zero.
- By Thursday July 30, 2026: signed identification delivered to the intermediary before midnight, day 45.
- Early August: purchase contracts signed on the identified properties, loan applications submitted, appraisals ordered.
- Late September: financing conditions cleared, title commitments reviewed, closing dates locked.
- Late November, roughly day 160: the target closing, leaving room for a two-week slip.
- Saturday December 12, 2026, day 180: the outside date, which in practice means funding by Friday December 11.
- Any identified property not received by then is taxable, and the intermediary releases what is left after day 180.
Related questions
If I identify on day 10, do I get 180 days from then?
No. The 180 days runs from your sale closing regardless of when the notice goes in, so identifying on day 10 gives you 170 days of closing time, not 180.
What happens if the replacement closes on day 181?
The statute treats property received after the exchange period as property that is not like-kind, so the gain attributable to it is recognized. There is no partial credit for being one day late on a property that was properly identified.
Is there any structure that gives more than 180 days?
No. A reverse exchange under Rev. Proc. 2000-37 caps the combined parking period at 180 days, and a build-to-suit exchange has to be finished inside the same 180 days, which is why improvements have to be scoped to what can actually be built in that window.
Can I add a property to the list on day 60 if the 180 days is still running?
No. The identification period closes at midnight on day 45 and the remaining 135 days are only for closing on what is already named. What you can and cannot revise after day 45 is set out here.
Do the 45 and 180 days run from my sale or from each separate replacement purchase?
From the sale. Buying three replacement properties does not create three timelines; every one of them has to be received before the single day 180.
Do I have to identify before I can make an offer on a property?
No. You can tour, negotiate, sign contracts and open escrow at any point in the 180 days; the identification notice is a separate written document delivered to your intermediary by midnight on day 45. How that notice has to be written and delivered is covered here.
Sources
Checked against these publications on September 19, 2026. Rules and figures change; confirm the current version with your CPA or attorney before you act. This page is general information, not tax or legal advice.
- 26 U.S.C. §1031(a)(3) (Cornell LII)
- 26 CFR §1.1031(k)-1(b) and (c)(1) (Cornell LII)
- IRS Fact Sheet FS-2008-18, Like-Kind Exchanges Under IRC Section 1031
- Rev. Proc. 2000-37, section 4.02(6) (Internal Revenue Bulletin 2000-40)
- IPX1031: Deadlines and identification requirements
- 1031 CORP: 180 from closing to closing