The Exact 45 and 180 Day 1031 Exchange Deadlines on a South Bay Sale

Published August 10, 2026

Both 1031 exchange clocks start on the same day, the day you close on the property you're selling, not the day you find a buyer or sign a contract. The identification period runs 45 days, the exchange period runs 180 days or your tax return due date, whichever comes first.

The short answer

Both 1031 exchange clocks start on the same date: the day you close and transfer title on the property you're selling, the relinquished property. You have 45 calendar days from that date to identify replacement property in writing, per Treasury Regulation section 1.1031(k)-1(b)(2). You have until the earlier of 180 calendar days after that same date, or the due date, including extensions, of your tax return for the year of the sale, to actually close on the replacement.

Last verified: August 10, 2026

Both deadlines run from one date, and it's not the one people assume

The single most common mistake in a South Bay 1031 exchange is starting the clock on the wrong day. It isn't the day you list the property, the day you accept an offer, or the day you sign a purchase and sale agreement. Under Treasury Regulation section 1.1031(k)-1(b)(2), confirmed in the Form 8824 instructions, the identification period and the exchange period both begin on the date the taxpayer transfers the relinquished property. That's the closing date on your sale, the day title actually passes.

If you close on your South Bay rental on a Tuesday, day one of both clocks is that Tuesday, and both periods run forward from there in calendar days, including weekends and holidays. There is no extension for a deadline that lands on a Saturday or a federal holiday under the general 1031 timing rules.

The 45-day identification period

You have 45 calendar days from the closing date of the relinquished property to identify replacement property in writing, either in a document you sign yourself or in a written agreement signed by all parties to the exchange, per the regulation. That written identification has to be delivered to the party responsible for holding the exchange, typically your qualified intermediary, before midnight on day 45.

There's no grace period. If day 45 falls on a Sunday, the deadline is still that Sunday. This is a hard stop, and it's the deadline that catches South Bay sellers off guard most often, because 45 days is not a long runway to find, negotiate, and put a replacement property under contract in a competitive coastal market like Hermosa Beach, Manhattan Beach, or Redondo Beach.

The 180-day exchange period, and the trap inside it

You must actually close on the replacement property by the earlier of two dates:

1. The 180th calendar day after you transferred the relinquished property, or
2. The due date, including extensions, of your federal tax return for the year the relinquished property was transferred.

That second prong is the part sellers routinely miss. If you close your sale late in the year, say in November, your 180th day runs into the following spring, past the normal April 15 filing deadline for the year of sale. Without a filed extension, your exchange period gets cut short by your return's due date, not the full 180 days.

The fix is mechanical: file a timely extension for the tax year of the sale (Form 4868 for individuals) if your 180th day falls after your original filing deadline. That extension pushes your effective filing deadline to October, which in turn preserves your full 180-day exchange window. Filing your return early, before completing the exchange, can also inadvertently cut the window short, since filing itself sets the due date interaction in motion.

Worked example

| Event | Date | Days from transfer |

|---|---|---|

| Close and transfer relinquished South Bay property | October 15 | Day 0 |

| Identification deadline | November 29 | Day 45 |

| Original tax return due date (no extension) | April 15 (following year) | Day 182 |

| 180-day exchange deadline | April 13 (following year) | Day 180 |

In this example the 180-day mark (April 13) falls two days before the unextended return due date (April 15), so the 180-day figure controls and the seller has the full window. Shift the closing date later in the year, or land on a leap year, and the ordering can flip, which is exactly why this needs to be checked against the actual calendar for your transaction rather than assumed.

What "identify" actually requires

Identification under the 45-day rule isn't a verbal conversation with your intermediary or a property you're "thinking about." The regulation requires replacement property to be designated in writing, unambiguously described, typically by legal description or street address, and delivered to the intermediary or another party to the exchange before the deadline. You can identify up to three properties without regard to value (the three-property rule) or more than three if their combined value doesn't exceed 200 percent of what you sold, under separate identification rules in the regulation not detailed further here.

FAQ

Does the clock start when I go into escrow, or when escrow closes?

When escrow closes and title actually transfers. Going into contract or opening escrow does not start either the 45-day or 180-day period.

Can I get an extension on the 45-day identification deadline?

No. The regulation provides no general extension mechanism for the 45-day period. Certain federally declared disasters have triggered IRS relief extending 1031 deadlines in specific years and regions, but that is case-specific relief, not a standing extension.

What happens if I miss the 45-day deadline?

The exchange fails as a tax-deferred 1031 exchange. Your sale is treated as a taxable transaction, and gain, including any depreciation recapture, is recognized in the year of sale.

Does filing my tax return early hurt my exchange?

It can. Filing your return for the year of transfer before your exchange period would otherwise run its course can be treated as ending your exchange period early, since the due date interaction under the regulation runs off the return itself. Coordinate the filing date with your intermediary and CPA before submitting a return in the middle of an open exchange.

Do the 45 and 180 day periods run concurrently or back to back?

Concurrently. Both start on the same transfer date. The 45-day period is not added on top of the 180-day period, it's the first 45 days inside the same 180-day (or shorter, due-date-limited) window.

This is general information, not tax advice. Confirm your specific closing dates, filing deadlines, and identification requirements with a qualified intermediary and a CPA or tax attorney before relying on any date in a real transaction.

Topics: taxes, 1031 exchange, capital gains, deadlines, South Bay

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