1031 Exchange Deadline Calculator

Enter the date you closed on the relinquished property (the property you sold). The calculator shows your exact identification deadline (Day 45) and exchange completion deadline (Day 180), adjusted for weekends and federal holidays per IRC §7503 — plus a warning if your window extends past the April 15 tax return deadline.

How the 1031 timing rules work

The two hard deadlines

Under IRC §1031(a)(3) and Treas. Reg. §1.1031(k)-1(b), a forward 1031 exchange has two irrevocable deadlines:

1. Day 45 — Identification Deadline. You must identify your replacement property (or properties) in writing to the qualified intermediary by midnight of the 45th calendar day after closing on the relinquished property. No extensions, no exceptions — missing Day 45 kills the exchange entirely.
2. Day 180 — Exchange Completion Deadline. You must close on the replacement property by midnight of the 180th calendar day after closing on the relinquished property (or by your tax return due date for that year, whichever is earlier). Missing Day 180 also kills the exchange.

"Calendar days" means exactly that — weekends and holidays count. The only relief is IRC §7503, which moves a deadline to the next business day if it falls on a Saturday, Sunday, or federal legal holiday. This calculator applies §7503 automatically.

Identification rules: what counts as identified

The identification must be in writing, signed by you, and delivered to the qualified intermediary (or another party to the exchange) before midnight of Day 45. Phone calls and verbal agreements don't count.

You have three ways to identify replacement properties:

• Three-Property Rule (most common): Identify up to 3 properties regardless of their aggregate value. You only need to close on one.
• 200% Rule: Identify any number of properties as long as their total fair market value doesn't exceed 200% of the relinquished property's sale price.
• 95% Rule: Identify any number of properties at any value, but you must acquire at least 95% of the total identified value. This rule is rarely used and practically difficult to satisfy.

You can change your identification before midnight of Day 45. After Day 45, you're locked in to whatever you identified — you can't add properties or substitute new ones.

The tax return extension trap

IRC §1031(a)(3)(B) says the exchange period ends at the earlier of 180 days or "the due date (determined with regard to extension) for the transferor's return." For calendar-year individual filers:

• Without extension: Tax return is due April 15. If your 180-day window extends past April 15, your effective exchange deadline is April 15 — not Day 180.
• With extension (Form 4868): Tax return is extended to October 15. Your exchange deadline reverts to the full Day 180 window.

This trap catches investors who close in mid-to-late October through December. The 180-day window extends past April 15 of the following year, and if they don't file a timely extension, they lose 1–3 months of exchange time without realizing it. The calculator flags this automatically.

What counts as the "closing date" (Day 0)

Day 0 is the date the deed transfers and the sale closes — typically the date your settlement statement reflects. It is not the contract date, the date the QI sets up the escrow account, or the date you receive funds. For a deferred exchange, the day the relinquished property deed is recorded is Day 0. If you're unsure, match this date to the date on your HUD-1 or Closing Disclosure.

Federal holidays that affect deadlines (§7503)

The following federal holidays can shift a 1031 deadline to the next business day if it falls on that date. The calculator applies these adjustments for 2025 through 2027 using algorithmically computed observed dates (e.g., when July 4 falls on Saturday, the observed holiday is Friday July 3):

• New Year's Day (Jan 1)
• Martin Luther King Jr. Day (3rd Mon, Jan)
• Presidents Day (3rd Mon, Feb)
• Memorial Day (last Mon, May)
• Juneteenth (Jun 19)
• Independence Day (Jul 4)
• Labor Day (1st Mon, Sep)
• Columbus Day (2nd Mon, Oct)
• Veterans Day (Nov 11)
• Thanksgiving Day (4th Thu, Nov)
• Christmas Day (Dec 25)

Reverse and improvement exchanges

This calculator handles forward (deferred) exchanges only. Reverse exchanges (where you acquire the replacement property before selling the relinquished property) follow different timing rules under Rev. Proc. 2000-37 — the 45/180-day framework applies but in reverse, and an Exchange Accommodation Titleholder (EAT) holds title to the parked property. The same 45-day identification window and 180-day overall exchange period apply. If you're doing a reverse exchange, your QI's documentation will control your specific dates.

Common mistakes that kill 1031 exchanges

• Missing Day 45 by one day. Absolutely fatal. The IRS has no authority to grant extensions on the identification deadline — it's statutory. Build in buffer. Don't rely on faxing or emailing at 11:59 PM.
• Not filing Form 4868 when needed. If you close in November and your 180-day window extends past April 15, you must file an extension by April 15 to get the full window. This is easy to miss if your CPA doesn't flag it.
• Identifying too many properties under the Three-Property Rule. If you identify 4 properties without qualifying under the 200% Rule, none of them qualify — you've violated all three identification rules and the exchange fails.
• Receiving "boot." If cash from the sale passes through your hands at any point (not through the QI), it's treated as boot (taxable proceeds), even if you later wire it to the replacement property. Always use a QI from Day 0, before closing.
• Related-party traps. Buying from a related party (spouse, siblings, parents, entities you control) triggers special rules under IRC §1031(f) that require a 2-year holding period from the exchange date. If the related party sells within 2 years, the original deferral is recaptured.
• Assuming the deadline is "business days." The 45- and 180-day periods are calendar days, full stop. The only business-day relief is for the deadline day itself (§7503). Day 44 does not become Day 41 because of holidays in between.

Legal basis: Identification and exchange period rules: IRC §1031(a)(3); Treas. Reg. §1.1031(k)-1(b). Business-day adjustment: IRC §7503. Tax return due date interaction: IRC §1031(a)(3)(B). Three-Property Rule, 200% Rule, 95% Rule: Treas. Reg. §1.1031(k)-1(c). Reverse exchange safe harbor: Rev. Proc. 2000-37. Related-party rules: IRC §1031(f).