1031 Exchange Timeline: 45-Day and 180-Day Rules Explained
A 1031 exchange lives or dies on two dates. Miss either one and the IRS treats your sale as a fully taxable event, no matter how well you structured everything else. This page walks through exactly how the clock works: when it starts, what has to happen by day 45, what has to happen by day 180, and the year-end trap that catches investors who close a sale too late in the calendar year.
This is a timing explainer, not a full exchange guide. It assumes you already know a 1031 exchange lets an investor defer capital gains tax by reinvesting sale proceeds into “like-kind” real property. If you need the tax math behind why that deferral matters, our Model Library has a full worked worksheet; this page is about the calendar.
The Rule, In One Sentence
Under 26 U.S.C. § 1031(a)(3), replacement property stops qualifying as like-kind unless the taxpayer (A) identifies it in writing within 45 days of closing on the relinquished property, and (B) actually receives it within 180 days of that same closing, or by the due date of that year’s tax return, whichever comes first. Both windows start on the same day and run at the same time. The 180-day period is not something that begins after the 45-day period ends.
Who This Applies To
Since the Tax Cuts and Jobs Act took effect for exchanges completed after December 31, 2017, Section 1031 only covers real property. The statute now reads: no gain or loss is recognized “on the exchange of real property held for productive use in a trade or business or for investment if such real property is exchanged solely for real property of like kind which is to be held either for productive use in a trade or business or for investment” (26 U.S.C. § 1031(a)(1)). Equipment, vehicles, and other personal property that used to qualify for like-kind treatment no longer do. If you’re exchanging investment or business real estate for other investment or business real estate, you’re in the right place.
Day Zero: The Clock Starts at Closing
Both deadlines are measured from a single event: the date you transfer the relinquished property. Treasury Regulation § 1.1031(k)-1(b)(2) defines the identification period as beginning “on the date the taxpayer transfers the relinquished property and ends at midnight on the 45th day thereafter.” The exchange period runs on the same start date and ends at midnight on the earlier of the 180th day or your tax return due date, extensions included.
Three things trip people up here:
- It’s the closing date on your relinquished property, not the contract date. Signing a purchase agreement doesn’t start the clock. The deed recording or the funds actually changing hands does.
- These are calendar days, not business days. Weekends and federal holidays count. The regulation text gives no weekend-extension allowance. If day 45 or day 180 lands on a Saturday, that’s still your deadline.
- The two periods run in parallel, not in sequence. You have 180 days total to close on replacement property, and 45 of those days are also your identification window. You don’t get 45 days to identify and then a fresh 180 days to close.
Days 1–45: The Identification Window
Within 45 days of your closing, you have to identify, in writing, the specific replacement property or properties you intend to acquire. “I’m looking at a few options” doesn’t satisfy this. The identification has to be a signed document describing the property (street address or legal description) and delivered to a party involved in the exchange who isn’t you or someone related to you, in practice your qualified intermediary.
You don’t have to identify only one property. Treasury Regulation § 1.1031(k)-1(c)(4) gives you three ways to do it:
- The three-property rule. Identify up to three properties, regardless of their value. This is the one most investors use.
- The 200% rule. Identify any number of properties, as long as their combined fair market value doesn’t exceed 200% of what you sold the relinquished property for.
- The 95% rule. If you identify more properties than the first two rules allow, the identification still holds if you end up acquiring at least 95% of the total value of everything you identified. In practice this rule is a fallback, not a strategy; missing it by even a few percentage points can unwind the whole exchange.
The practical move: identify more than you plan to actually close on. If your primary target falls through during due diligence, you want backup properties already on the list, because you can’t add anything after day 45. You can revoke or replace an identification before the deadline passes, but once day 45 is gone, your list is locked.
Days 46–180: The Closing Window
You have until the earlier of day 180 or your tax return due date (with extensions) to actually close on the replacement property identified during the first window. For most exchanges that close in the first three quarters of the year, 180 days is the binding constraint and the tax-return due date never comes into play, because your return for that tax year isn’t due until well after day 180.
The trap shows up when you close the relinquished property late in the year. Say you sell in mid-November. Your 180th day lands in mid-May of the following year, but if you’re an individual filer and don’t extend, your tax return for that sale year is due April 15, several weeks earlier. Under IRC § 1031(a)(3)(B)(ii), the exchange period ends at the earlier date, meaning your actual closing window is shorter than 180 days.
The fix is straightforward: file an extension (Form 4868 for individuals) for the tax year in which you sold the relinquished property. Because the statute measures the due date “with regard to extension,” filing the extension pushes your effective exchange deadline out to October 15, restoring the full 180 days. Investors who close deals in the fourth quarter and skip the extension are the ones who lose weeks of runway without realizing it until it’s too late to fix.
Timeline at a Glance
Here’s how the two windows actually play out using a real closing date, March 2, 2026, walked forward using calendar-day counting the way the regulation requires.
| Milestone | Rule | Example date |
|---|---|---|
| Day 0: Relinquished property closes | Clock starts on the transfer date | March 2, 2026 (Monday) |
| Day 45: Identification deadline | Written, signed identification delivered to your QI | April 16, 2026 (Thursday) |
| Day 180: Exchange period ends | Must have title to replacement property, unless your tax return due date is earlier | August 29, 2026 (Saturday) |
Notice day 180 in this example lands on a Saturday. That’s deliberate: it’s a reminder that the exchange period does not shift to the next business day. If your closing attorney or title company can’t fund and record on a weekend, you need your closing scheduled with days to spare, not on the deadline itself.
Why You Can’t Hold the Money Yourself
None of the above works if you touch the sale proceeds. If you have actual or constructive receipt of the funds from the relinquished property sale, even briefly, the exchange fails and the transaction is taxed as an ordinary sale (Treas. Reg. § 1.1031(k)-1(f)). This is why every deferred exchange runs through a qualified intermediary.
The safe harbor is in Treasury Regulation § 1.1031(k)-1(g)(4): a qualified intermediary who is not you or a disqualified person, who enters into a written exchange agreement with you, and who acquires the relinquished property, transfers it to the buyer, acquires the replacement property, and transfers it to you, shields you from constructive receipt during the process. The proceeds sit with the intermediary the entire time, never in your bank account.
Engage the intermediary before you close on the relinquished property, not after. A common and expensive mistake is closing a sale first and trying to set up the exchange afterward. Once the closing has happened and proceeds have gone anywhere other than a qualified intermediary, the exchange structure is no longer available for that transaction.
What Happens If You Miss a Deadline
There’s no informal grace period. Miss the 45-day identification deadline and none of your intended replacement property qualifies, full stop. Miss the 180-day (or earlier tax-return-due-date) closing deadline and the exchange fails even if you already identified the right property. In both cases the sale of your relinquished property becomes a standard taxable sale for that year, and any deferred gain is recognized.
The narrow exception is IRS disaster relief. When a federally declared disaster affects a taxpayer, a relinquished property, or a party to the exchange, the IRS can issue relief that postpones 1031 deadlines for taxpayers in the affected area. This relief is announced case by case through IRS guidance tied to specific disasters, not a standing rule you can plan around, so don’t assume it applies unless the IRS has specifically issued relief covering your situation.
If you can see a 45-day or 180-day deadline is going to be a problem before you’ve even closed on the relinquished property, a reverse exchange is worth discussing with your qualified intermediary and CPA. Under the safe harbor in Rev. Proc. 2000-37, an exchange accommodation titleholder can take title to the replacement property first, before you’ve sold the relinquished property, which flips the order of operations and can relieve timeline pressure on the acquisition side. It’s a more expensive, more document-heavy structure than a standard forward exchange, and it isn’t a fix for a deadline you’ve already blown.
Common Timeline Mistakes
- Waiting until after closing to call a qualified intermediary. By then it’s often too late to set up the exchange at all.
- Treating the 45 days as a soft target. Verbal or informal notice to your broker doesn’t count. The identification has to be a signed document delivered to the right party before midnight on day 45.
- Assuming weekends push the deadline. They don’t. Build your closing schedule with buffer, not against the wire.
- Ignoring the same-taxpayer rule. The taxpayer that sells the relinquished property has to be the same taxpayer that takes title to the replacement property. Changing entities between the sale and the purchase, outside of a disregarded single-member LLC, can unwind the exchange.
- Forgetting the year-end due-date trap. If you’re closing your sale in the fourth quarter, confirm whether your 180th day falls after your unextended tax return due date, and file the extension if it does.
- Not identifying backups. If your primary replacement property falls out of contract after day 45, you’re out of options unless you identified alternates under the three-property or 200% rule.
Run the Numbers Before You Commit
Getting the calendar right only matters if the exchange is worth doing in the first place. Before you engage an intermediary or start shopping replacement property, run the actual deferred-gain math against a taxable sale for your specific deal, sale price, adjusted basis, depreciation recapture, and all. Our Model Library includes a full Depreciation & 1031 Exchange Worksheet that walks a real acquisition through both a taxable exit and a 1031 exchange side by side, so you can see the actual dollar difference before you’re 30 days into a 45-day identification window.