Calculators · Deadlines
45-Day and 180-Day Deadline Calculator
Enter the closing date of your sale and get the identification deadline, the exchange deadline and the earlier tax-return due date that can cut the 180 days short.
What this calculator does
Section 1031 gives you 45 calendar days from the transfer of the relinquished property to identify replacement property in writing, and 180 calendar days to receive it. Both run from the same day and neither moves for a weekend or a holiday. The exchange period also ends on the due date of your tax return for the year of the sale, including extensions, if that comes first.
Enter the closing date. The calculator prints the dates, flags weekends, and shows the return-due-date trap for sales late in the year. If you are selling more than one property, see two sales weeks apart.
Your deadlines
How the numbers are calculated
Day one is the day after the transfer. The identification period ends at midnight on the 45th day and the exchange period on the 180th day after the transfer, as Reg. section 1.1031(k)-1(b)(2) defines them. The calculator adds 45 and 180 calendar days to the closing date.
For the return trap it assumes a calendar-year individual return due April 15 of the following year, extended to October 15 if you file Form 4868. Partnerships and corporations have different due dates; use the later-of-the-two logic with your own date.
No disaster postponement is applied. When an IRS notice covers you, the postponement under Rev. Proc. 2018-58 section 17 adds 120 days to whichever deadline falls in the covered window, and section 4 can push a deadline to the notice's end date; the notice controls.
Questions about this calculator
Does the 45-day deadline move if it falls on a weekend or holiday?
No. Both periods are calendar days and end at midnight on day 45 and day 180 with no roll-forward for weekends or holidays. See weekends and holidays.
What is the tax-return trap?
The exchange period ends on the earlier of 180 days or the due date of your return, including extensions, for the year of the sale. A December sale with an April 15 due date leaves fewer than 180 days unless you file for an extension. See keeping all 180 days with an extension.
Can a disaster declaration extend these dates?
Only when the IRS issues a notice covering you under Rev. Proc. 2018-58, which can postpone a deadline or add 120 days. The calculator does not apply any extension; see extending the deadlines.
When exactly does day one start?
The day after the relinquished property transfers, which is the closing and funding date in practice, not the recording date. See when the 45-day clock starts.
Sources
Figures checked on September 30, 2026. Rates and thresholds change each year; this page is general information, not tax or legal advice.
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