What are the 45- and 180-day rules?
A 1031 exchange runs on two strict deadlines that start the day you sell. You have 45 days to identify replacement property in writing, and 180 days total to close on it. The 45-day window sits inside the 180. Miss either — even by a day — and the exchange fails.
Both clocks start at the sale
The countdown begins the day your relinquished property (the one you’re selling) closes. From that day, the 45-day and 180-day clocks run concurrently — you do not get 225 days. The identification deadline arrives first; the closing deadline arrives later, inside the same overall window.
| Day 0 | Relinquished property closes — both clocks start |
| By day 45 | Identify replacement property in writing to your QI |
| By day 180 | Close on the replacement (or your tax-return due date, if earlier) |
The Q4 trap
The 180-day period ends on day 180 or your tax-return due date for the sale year, whichever comes first. Sell late in the year and your window can be cut short — unless you file a tax-return extension to preserve the full 180 days. This catches investors off guard on fourth-quarter sales.
The identification rules
Your written identification (by day 45) has to follow one of three rules:
- Three-property rule. Identify up to three properties of any value.
- 200% rule. Identify any number of properties, as long as their combined value doesn’t exceed 200% of what you sold.
- 95% rule. If you exceed both limits, you must actually acquire at least 95% of the total value you identified.
These deadlines don’t bend
They’re calendar days — weekends and holidays count — and the IRS grants no routine extensions (limited relief exists only for certain federally declared disasters). The practical takeaway: hire your qualified intermediary and line up replacement candidates before you sell. Forty-five days is tight once the clock is running.