The 1031 Exchange 45-Day Calculator Every Broker Should Bookmark

The 1031 exchange deadlines do not bend. Miss the 45-day identification window or the 180-day closing date by a single business day and the entire like-kind exchange collapses into a fully taxable sale. Brokers who run exchanges all year keep one mental model on a sticky note: relinquished property closes on Day 0, written identification is due by Day 45, and replacement property must close by Day 180, calendar days, no extensions for weekends, no exceptions for closing delays.

The two clocks: 45 and 180 days

Both clocks start the day after the relinquished property closes. The IRS treats the closing date as Day 0, and Day 1 is the next calendar day. Section 1031(a)(3) and Treas. Reg. 1.1031(k)-1(b)(2) define the windows in calendar days, not business days.

The 45-day clock requires a written, signed identification of replacement property delivered to the qualified intermediary (or another party to the exchange who is not a disqualified person) before midnight on Day 45. Email, fax, or hand delivery all work; verbal identification does not.

The 180-day clock requires the taxpayer to receive the replacement property by Day 180, or by the due date of their tax return for the year of the relinquished sale, including extensions, whichever comes first. This second condition catches many year-end exchanges. A property sold in November 2026 with no extension filed must close the replacement by April 15, 2027, not the full 180 days.

The two clocks run concurrently, not consecutively. Day 45 and Day 180 are both measured from the same closing date.

How weekends and federal holidays count

They count. The 45-day and 180-day deadlines fall on whatever calendar day they fall on, including Saturdays, Sundays, Christmas, and Thanksgiving. There is no automatic extension to the next business day under Section 1031.

This is the single biggest difference between 1031 deadlines and most other tax deadlines. Section 7503 of the Internal Revenue Code, which pushes deadlines falling on weekends or holidays to the next business day, does not apply to the 45 and 180-day periods because those are creatures of Section 1031, not the general filing rules.

The one exception worth knowing: federally declared disaster relief. The IRS periodically issues notices (recent examples include hurricane and wildfire zones) that extend 1031 deadlines by 120 days for affected taxpayers or properties. Check the IRS disaster relief page before assuming a hard deadline. Outside of declared disasters, plan as if Day 45 falling on a Sunday means the identification must be delivered by Friday.

Title companies and qualified intermediaries close on business days. If Day 180 lands on a Saturday, the practical deadline is the Friday before, and ideally several business days earlier to handle wire transfers, recording delays, and lender conditions.

The three identification rules

The taxpayer must identify replacement property under one of three rules. Pick one before Day 45:

Three-property rule. Identify up to three properties of any value. This is the default for most exchanges and the cleanest path. The taxpayer can close on one, two, or all three.

200% rule. Identify any number of properties as long as the total fair market value does not exceed 200% of the relinquished property's sale price. Useful for portfolio buyers assembling several smaller assets.

95% rule. Identify any number of properties of any value, but the taxpayer must close on properties representing at least 95% of the total identified value. Rarely used because missing a single deal usually breaks the 95% threshold.

Identification must describe each property unambiguously: typically a street address, legal description, or assessor parcel number. "A retail center in Phoenix" does not qualify. "1234 Main Street, Phoenix, AZ 85001" does.

The taxpayer can revoke and re-identify within the 45-day window in writing. After Day 45, the identified list is locked.

A worked example with real dates

A broker's client closes the sale of a relinquished industrial building on April 24, 2026 (Day 0).

• Day 1: April 25, 2026
• Day 45 (identification deadline): June 8, 2026, a Monday. Written identification must be delivered to the QI before midnight.
• Day 180 (closing deadline): October 21, 2026, a Wednesday. Replacement property must be acquired by this date.

Tax-return interaction: the seller is a calendar-year individual taxpayer. The 2026 return is due April 15, 2027. Because Day 180 (October 21, 2026) falls before the unextended return date, the 180-day clock controls. No extension issue here.

Now move the closing to November 15, 2026. Day 180 would be May 14, 2027, but the unextended 2026 return is due April 15, 2027. The taxpayer must either file Form 4868 to push the return deadline to October 15, 2027, or close the replacement by April 15, 2027. Brokers should flag this every November and December.

Common pitfalls that wreck exchanges

• Touching the proceeds. If sale funds hit the seller's account, even briefly, the exchange dies. Wire instructions go directly to the qualified intermediary at closing.
• Using a disqualified person as QI. The taxpayer's attorney, CPA, real estate agent, or anyone who has provided services in the prior two years cannot act as QI under Treas. Reg. 1.1031(k)-1(k).
• Identifying by category. "Any class A multifamily under $10M" is not a valid identification.
• Forgetting earnest money is part of the exchange. Deposits paid before the relinquished sale closes generally cannot come from exchange funds.
• Missing the boot. Cash received, debt paid down without replacement, or non-like-kind property received is taxable boot, even in a successful exchange.
• Assuming a deal will close. Identify backup properties under the three-property rule. A single-property identification with a failed closing means a fully taxable sale.
• Year-end timing. As above, the tax return due date can shorten the 180-day window. File the extension early.

A printable 45/180 day checklist

• Confirm exchange intent in the purchase and sale agreement (cooperation clause)
• Engage qualified intermediary before relinquished closing
• Verify QI is not a disqualified person
• Wire sale proceeds directly to QI escrow at closing
• Record Day 0 (relinquished closing date)
• Calendar Day 45 and Day 180 with two reminders each (Day 30 and Day 40; Day 150 and Day 170)
• Identify under three-property, 200%, or 95% rule in writing before Day 45
• Use unambiguous descriptions (address, APN, or legal description)
• Confirm tax return due date does not shorten Day 180; file extension if needed
• Send identification to QI by email and retain delivery confirmation
• Open escrow on identified properties early to absorb diligence delays
• Schedule replacement closing at least 5 business days before Day 180
• Confirm equal or greater value, equity, and debt to avoid boot
• Receive replacement property deed before midnight on Day 180

bipsio lets brokers tag any active mandate with a 45-day identification window so the calendar lives next to the inventory. Hugo, the built-in assistant, prioritizes matching inventory inside the window and flags any deal at risk of missing the 180-day close, useful when a client identifies three properties and one slips into retrade.

---

Disclaimer: This article is for general informational purposes only and is not tax, legal, or accounting advice. Section 1031 has nuances around related parties, partnership interests, vacation property, reverse exchanges, and improvement exchanges that are not covered here. Before initiating any like-kind exchange, consult a qualified intermediary and a CPA familiar with your client's specific situation.

Want to see how bipsio handles 1031 timelines alongside your inventory? sign up.