1031 Exchange Calculator: Find Your 45-Day and 180-Day Deadlines
Enter the closing date of the property you sold, and this calculator returns your two 1031 exchange deadlines: the 45th calendar day (your deadline to identify replacement property in writing) and the 180th calendar day (your deadline to close on it). Both clocks start on the same day — the date you transfer the relinquished property — and run at the same time, per IRC §1031(a)(3). The dates are calendar days, not business days, and they are not extended for weekends or holidays.
Enter the closing date of your relinquished property to calculate your 1031 exchange deadlines:
How the two deadlines actually work
The deadlines come straight from the statute. IRC §1031(a)(3) says replacement property does not qualify unless:
- It is identified on or before the day that is 45 days after the date you transfer the relinquished property, and
- It is received by the earlier of (i) the day that is 180 days after that transfer, or (ii) the due date (including extensions) of your tax return for the year of the transfer.
Three details trip people up:
- The clocks are concurrent, not sequential. You do not get 45 days to identify and then 180 more days to close. Both periods start on the transfer date, so after your 45-day identification window closes you have 135 days left to complete the purchase. See Treas. Reg. §1.1031(k)-1(b)(2), which defines the identification period as ending at midnight on the 45th day and the exchange period as ending at midnight on the 180th day (or the return due date, if earlier).
- They are exact calendar days. If day 45 lands on a Saturday, Sunday, or holiday, that is still your deadline. The regulations make no business-day adjustment. The only exception is a federally declared disaster (covered below).
- The 180-day deadline can be shorter than 180 days. Because the statute uses the earlier of the 180th day or your tax-return due date, a sale late in the year can quietly compress your exchange period — unless you file an extension.
The tax-return trap: why late-year exchanges need an extension
If you sell your relinquished property in roughly the last quarter of the year, your 180th day falls after the normal due date of your tax return for the year of sale. In that case, your real deadline is the return due date — not day 180 — unless you extend.
The Instructions for Form 8824 (the form on which every like-kind exchange is reported) state it plainly: the replacement property must be received by the earlier of the 180th day after the transfer or “the due date (including extensions) of your tax return for the year in which you transferred the property given up.”
The practical rule: if your 180-day window extends past your filing deadline, file an extension (Form 4868 for individuals) before filing your return. Filing the return first — even accidentally, even early — cuts your exchange period short. With a filed extension, you get the full 180 days.
The calculator above flags this automatically when your 180th day lands after the standard April 15 individual deadline. (Entities with different fiscal years or filing deadlines should map this against their own due dates.)
A worked example (hypothetical dates)
Suppose you close the sale of a rental property on March 10, 2026. This is a hypothetical for illustration:
| Milestone | Rule | Date |
|---|---|---|
| Transfer of relinquished property (day 0) | Clock starts | Tuesday, March 10, 2026 |
| Identification deadline (day 45) | Written ID delivered by midnight | Friday, April 24, 2026 |
| Exchange deadline (day 180) | Replacement property received | Sunday, September 6, 2026 |
Note that day 180 lands on a Sunday. It does not roll to Monday — the purchase must close by that Sunday, which in practice means closing the previous business day.
Now shift the sale to December 1, 2026:
| Milestone | Date |
|---|---|
| Identification deadline (day 45) | January 15, 2027 |
| 180th day | May 30, 2027 |
| Individual return due date | April 15, 2027 |
Here the 180th day (May 30) falls after the April 15 return due date, so without an extension the exchange period ends April 15, 2027 — about six weeks short of the full 180 days. Filing an extension restores the full period to May 30.
The identification rules: what “identify” means by day 45
Identification is not casual. Under Treas. Reg. §1.1031(k)-1(c), you must unambiguously describe the replacement property (a street address or legal description works) in a signed written document delivered by midnight of day 45 to the seller of the replacement property or another party to the exchange, such as your qualified intermediary — not to your own attorney or agent. Your identification must fit one of three rules:
- Three-property rule: up to three properties, regardless of their value.
- 200% rule: any number of properties, if their combined fair market value doesn’t exceed 200% of the value of what you sold.
- 95% rule: any number of properties of any value, but only if you actually acquire at least 95% of the total identified value.
You can revoke and replace identifications in writing at any time before the 45-day deadline — but not after. If you close on a replacement property within the first 45 days, that property is treated as identified. For a deeper look at eligible property types, see what qualifies for a 1031 exchange.
No extensions — except federally declared disasters
There is no procedure to request more time because financing fell through, a deal collapsed, or a party was slow. The one exception is a federally declared disaster. Under Section 17 of Rev. Proc. 2018-58, when the IRS issues disaster relief for a specific event, a 45-day or 180-day deadline falling on or after the disaster date is postponed by 120 days or to the last day of the general disaster extension period in the IRS relief notice, whichever is later — capped at the due date (including extensions) of your return for the year of transfer, and at one year.
You may qualify even if you don’t live in the disaster area — for example, if the relinquished or replacement property sits in the covered disaster area, or your qualified intermediary, lender, or title company is located there and the disaster prevents closing. Check the IRS news release for the specific disaster to confirm relief applies.
What to do when a deadline is at risk
If day 45 or day 180 is approaching and your plan is wobbling, the realistic options are:
- Identify backup properties. Use all three slots under the three-property rule (or the 200% rule if you’re identifying more). If your primary target falls through after day 45, you can only buy what you identified.
- Consider a DST as an identification backstop. The IRS ruled in Rev. Rul. 2004-86 that a beneficial interest in a qualifying Delaware Statutory Trust can be acquired as like-kind replacement property. Because DST interests are fractional and typically available for purchase quickly, some investors list one as a third identified property in case direct deals collapse. See our guide to DSTs in a 1031 exchange for the trade-offs.
- Check for disaster relief. If a federally declared disaster affected your transaction, the Rev. Proc. 2018-58 postponement above may apply.
- Consider a reverse exchange next time. If you already have the replacement property lined up, a reverse 1031 exchange under Rev. Proc. 2000-37 lets you acquire it before selling — trading deadline risk on the purchase for deadline risk on the sale.
- Understand the cost of a partial failure. If you close on less than you sold, or miss the deadlines entirely, the shortfall is taxed. Leftover cash or reduced debt is boot, taxable up to your realized gain.
Missing the 45-day deadline with no identified property, or the 180-day deadline with no closing, doesn’t trigger a penalty — it simply means the exchange fails and the sale is taxable as a normal sale.
Beyond the dates: what else the calculator can’t check
A calculator handles the arithmetic; a valid exchange needs more:
- A qualified intermediary in place before you close the sale. In a delayed exchange you cannot touch the proceeds — the safe harbor in Treas. Reg. §1.1031(k)-1(g) requires the QI to hold them. Compare providers in our guide to 1031 exchange companies.
- Qualifying property on both ends. Post-2017, only real property held for investment or business use qualifies — and your primary residence does not.
- Form 8824 filed with your return for the year you transferred the relinquished property (About Form 8824).
- State-level rules. Some states add withholding requirements or claw back deferred gains. See our state-by-state guides.
Frequently asked questions
Both the 45-day identification period and the 180-day exchange period begin on the date you transfer the relinquished property — generally the closing date of your sale. They run concurrently, so after the 45-day identification window ends you have 135 days remaining to close on the replacement property.
No. The identification and exchange periods are measured in exact calendar days, and the regulations make no adjustment for weekends or holidays. If day 45 falls on a Sunday, the written identification is still due by midnight that Sunday. The only exception is relief issued for a federally declared disaster under Rev. Proc. 2018-58.
Not on request. The only postponement is for federally declared disasters, where Rev. Proc. 2018-58 extends qualifying deadlines by 120 days or to the end of the IRS's general disaster relief period, whichever is later. Separately, if you sold late in the year, filing a tax return extension preserves your full 180 days — because the exchange period otherwise ends on your return's due date if that comes first.
Your exchange period ends on the earlier of the 180th day or the due date of your tax return (including extensions) for the year of the sale. For an individual who sells on December 1, day 180 falls around May 30 — after the April 15 filing deadline — so without filing an extension the exchange period is cut short at April 15. File the extension before filing your return to keep the full 180 days.
You can only acquire property you identified during the 45-day window, so if every identified property falls through, the exchange fails and the sale becomes taxable. That is why many investors identify the maximum three properties, sometimes including a Delaware Statutory Trust interest as a backup, since the IRS held in Rev. Rul. 2004-86 that qualifying DST interests count as like-kind real property.
This page is for educational purposes only and is not legal or tax advice. 1031 exchanges are governed by IRC §1031 and related Treasury Regulations; consult a qualified tax professional or attorney about your specific situation.
Primary sources: IRC §1031 · Treas. Reg. §1.1031(k)-1 · Instructions for Form 8824 · About Form 8824 · Rev. Proc. 2018-58 · Rev. Proc. 2000-37 · Rev. Rul. 2004-86
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