The 1031 Exchange 45-Day Rule
In a 1031 exchange, the 45-day rule requires you to identify your potential replacement property in writing within 45 calendar days of transferring the relinquished property. Under Treas. Reg. §1.1031(k)-1(b), the identification period “begins on the date the taxpayer transfers the relinquished property and ends at midnight on the 45th day thereafter” — weekends and holidays included, with no extensions except for federally declared disasters. Miss it, and the exchange fails: your sale becomes fully taxable.
How the 45-day clock works
The clock starts on the day you close the sale of the relinquished property (the date of transfer) and runs in calendar days — not business days. Day 45 ends at midnight, and your written identification must be delivered by then.
| Question | Answer | Source |
|---|---|---|
| When does the clock start? | The date you transfer (close on) the relinquished property | Treas. Reg. §1.1031(k)-1(b)(2)(i) |
| Calendar days or business days? | Calendar days — weekends and holidays count | IRS FS-2008-18 |
| When exactly is it due? | Midnight at the end of the 45th day | Treas. Reg. §1.1031(k)-1(b)(2)(i) |
| Does it pause the 180-day deadline? | No — both periods run concurrently from the same start date | Treas. Reg. §1.1031(k)-1(b)(2) |
| Can it be extended? | Only for federally declared disasters | Rev. Proc. 2018-58, §17 |
The 45-day identification period and the 180-day exchange period run concurrently from the same transfer date — identifying on day 45 leaves you only 135 more days to close. And the 180-day period itself ends at midnight on the earlier of the 180th day or the due date (including extensions) of your tax return for the year of the transfer, so exchanges started late in the year may need a filing extension to get the full 180 days.
Hypothetical timeline (illustration only): you close the sale of a rental property on Wednesday, March 4, 2026. Day 45 is Saturday, April 18, 2026 — and because the deadline falls on a Saturday, it is still Saturday at midnight; it does not roll to Monday. Day 180 is Monday, August 31, 2026.
What counts as a valid identification
The 45-day rule is not satisfied by “looking at properties” or telling your agent what you like. Under Treas. Reg. §1.1031(k)-1(c), a valid identification must be:
- In writing. A written document — in practice, almost always the identification form your qualified intermediary provides.
- Signed by you (the taxpayer).
- Unambiguous. Real property must be described by “a legal description, street address, or distinguishable name.” “A duplex somewhere in Austin” doesn’t cut it.
- Delivered on time to a permitted party. Hand delivered, mailed, faxed, or otherwise sent before the end of the identification period to either the person obligated to transfer the replacement property to you (typically the seller) or “any other person involved in the exchange other than the taxpayer or a disqualified person” — in practice, your qualified intermediary. Notice to your own attorney, real estate agent, or accountant is not sufficient, per the IRS’s like-kind exchange fact sheet.
Two useful shortcuts in the regulation:
- Property you actually receive within the 45 days is automatically identified. Per §1.1031(k)-1(c)(1), “any replacement property that is received by the taxpayer before the end of the identification period will in all events be treated as identified.” Close on the replacement in the first 45 days and no separate identification letter is needed for it.
- Identification in a signed exchange agreement counts. An identification made in a written agreement for the exchange, signed by all parties before the end of the period, satisfies the requirement.
How many properties can you identify? The 3-property, 200%, and 95% rules
You don’t have to identify just one property — the regulation gives you three alternative limits under Treas. Reg. §1.1031(k)-1(c)(4):
| Rule | What it allows |
|---|---|
| 3-property rule | Up to three properties of any value — the regulation says “without regard to the fair market values of the properties.” There is no price cap. |
| 200% rule | Any number of properties, as long as their combined fair market value doesn’t exceed 200% of the value of what you sold. |
| 95% rule | If you exceed both limits above, the identification still survives if you actually acquire, by the end of the exchange period, identified property worth at least 95% of the total value of everything you identified. |
Most investors use the 3-property rule because it’s simple and has no value limit. A common misconception — repeated on many websites — is that the three properties must collectively stay under some value threshold. They don’t; the value limits only apply under the 200% and 95% alternatives.
You don’t have to buy everything you identify. Identifying three properties and closing on one is perfectly fine. (If you buy less than you sold, the difference generally comes back to you as taxable boot.)
No weekend or holiday extensions
If day 45 lands on a Saturday, Sunday, or federal holiday, the deadline is still that day. The IRS is explicit in its like-kind exchange fact sheet (FS-2008-18):
“These limits cannot be extended for any circumstance or hardship except in the case of presidentially declared disasters.”
The general “next business day” convention that applies to many tax filing deadlines does not apply here — the regulation fixes the deadline at midnight on the 45th day, full stop. Plan to deliver your identification days early, not at 11:58 p.m. on a holiday weekend.
The only exception: federally declared disasters
When the President declares a disaster and the IRS issues a relief notice for it, Rev. Proc. 2018-58, Section 17 can postpone 1031 deadlines. The mechanics:
- A 45-day or 180-day deadline that falls 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 notice, whichever is later.
- The postponement can never extend beyond (a) the due date, including extensions, of your tax return for the year of the transfer, or (b) one year.
- You qualify only if the relinquished property was transferred on or before the disaster date, and you’re either an “affected taxpayer” under the IRS notice or you have difficulty meeting the deadline for a listed disaster-related reason — for example, the relinquished or replacement property sits in the covered disaster area, a party to the transaction (QI, lender, title company, settlement attorney) is based there, exchange documents were destroyed, or a lender or title insurer pulled out because of the disaster.
- There’s even limited retroactive relief: if your 45-day deadline passed before the disaster but a property you had identified is substantially damaged by it, Section 17.03 postpones that already-expired identification deadline.
None of this is automatic in the everyday sense — it hinges on a specific IRS disaster notice covering your situation. Current relief notices are posted on the IRS disaster relief page. If you think one applies, confirm with your QI and tax advisor before relying on it.
Changing your mind before day 45
Identification is not one-shot. Under Treas. Reg. §1.1031(k)-1(c)(6), you may revoke an identification at any time before the end of the identification period — in a written document, signed by you, delivered to the same person who received the original identification — and identify different properties in its place. Savvy exchangers use this: identify early, keep shopping, and swap out weaker candidates as better deals surface. After midnight on day 45, the list is frozen; the property you ultimately receive must be substantially the same as property you identified.
What happens if you miss the deadline
If day 45 passes with no valid identification, the exchange fails:
- The entire gain becomes taxable. With nothing identified, there is no like-kind exchange to complete — the sale is treated as a taxable sale, including any depreciation recapture.
- Your money stays locked up briefly anyway. Under the safe-harbor rules of Treas. Reg. §1.1031(k)-1(g)(6), your exchange agreement must restrict your access to the funds; if you identify nothing, the QI can generally return the proceeds after the 45-day period ends.
- Timing of the tax can shift. If your sale closed late in the year and the failed exchange pays out the following January, the gain may be reportable in the year you actually receive the funds under the installment-sale coordination rules of §1.1031(k)-1(j)(2) — a question for your CPA, and one reason failed exchanges still get reported carefully on Form 8824 and related forms.
Partial misses hurt too: identify properties but buy less than you sold, and leftover funds come back as taxable boot, recognized up to your realized gain under IRC §1031(b).
The DST backstop
One reason Delaware statutory trusts are popular with exchangers on a deadline: in Rev. Rul. 2004-86, the IRS ruled that a beneficial interest in a properly structured DST holding real estate is treated as a direct interest in the underlying real property for §1031 purposes — not as a disqualified trust certificate. Because DST interests are fractional and offerings are typically already-closed, stabilized properties, many investors use one of their three identification slots for a DST as insurance. If the primary deal dies after day 45, the DST slot can still absorb the exchange funds — often in a precise dollar amount. The trade-off is passivity: DSTs are structured with severely limited trustee powers, so you give up control.
Practical identification strategy
- Start shopping before you sell. The 45 days go fast; most successful exchangers are already negotiating on replacements when the relinquished property closes.
- Use all three slots. Under the 3-property rule, identify a primary target plus one or two backups (a DST is a common third slot).
- Describe properties precisely. Street address or legal description on the QI’s form — an ambiguous identification is an invalid one.
- Deliver to the QI, in writing, signed — early. Don’t rely on your own agent or attorney having “been told.” Get written confirmation of receipt.
- Refine before day 45. Revoke and substitute in writing while you still can; after midnight on day 45 the list is locked.
- Mind the calendar. Deadlines don’t move for weekends or holidays, and the 45- and 180-day clocks run concurrently. Map your dates with our 1031 exchange calculator.
The 45-day rule is federal law and identical in every state, though state tax treatment of the deferred gain varies — see our state-by-state 1031 guides for local considerations.
Frequently asked questions
No. The identification period ends at midnight on the 45th calendar day after you transfer the relinquished property, regardless of weekends or holidays. The IRS states the time limits cannot be extended for any circumstance or hardship except presidentially declared disasters, where Rev. Proc. 2018-58 and the specific IRS disaster notice can postpone the deadline.
No. Under the 3-property rule in Treas. Reg. §1.1031(k)-1(c)(4), you may identify up to three properties without regard to their fair market values. Value limits only apply if you identify more than three properties — then the 200% rule (aggregate value up to twice what you sold) or the 95% fallback (actually acquire 95% of the value identified) must be satisfied.
Yes, but only before the deadline. You can revoke an identification at any time before midnight of day 45 in a signed written document delivered to the same person who received the identification, and identify different properties instead. After day 45, the list is locked.
The exchange fails and your sale becomes fully taxable, including depreciation recapture. Under the safe-harbor rules your qualified intermediary generally returns the proceeds after the identification period ends. If the payout lands in the following tax year, the timing of the recognized gain is determined under the installment-sale coordination rules — worth reviewing with a CPA.
No — they run concurrently, both starting on the date you transfer the relinquished property. Identifying on day 45 leaves 135 days to close. The exchange period also ends at your tax return due date (including extensions) if that comes before day 180, so late-year exchanges may require filing an extension.
This article is for educational purposes only and is not legal or tax advice. The identification rules are governed by IRC §1031 and Treas. Reg. §1.1031(k)-1, and disaster relief depends on specific IRS notices; consult a qualified tax professional or attorney about your specific situation and deadlines.
Primary sources: IRC §1031 (Cornell LII) · Treas. Reg. §1.1031(k)-1 (Cornell LII) · IRS Fact Sheet FS-2008-18, Like-Kind Exchanges · Rev. Proc. 2018-58 (IRS) · IRS Tax Relief in Disaster Situations · Rev. Rul. 2004-86 (IRB 2004-33) · IRS Form 8824