1031 Exchange Deadline Calculator

How the 45-day and 180-day periods work

In a 26 U.S.C. 1031(a)(3) real-estate swap, two clocks start when you give up your old land. Under 26 CFR 1.1031(k)-1(b)(2), that deed closing day under section 1001(a) is Day 0. Day counting starts the next morning. You have 45 days to name new land by midnight on day 45. You must get the new land by midnight on day 180 or your tax return due date, whichever comes first. Extensions count toward that return due date. If one deal gives up two tracts on two days, 26 CFR 1.1031(k)-1(b)(2)(iii) starts both clocks on the first day.

A tax return due date can arrive before day 180 on a late-year sale. Under 26 U.S.C. 6072(a), April 15 is the due date for Form 1040, Form 1041 and Form 1120 filers. In 2026, day 180 ties April 15, 2027 on Saturday, October 17, 2026. A sale on Sunday, October 18, 2026 drops to 179 days without an extension. Under 26 U.S.C. 6072(b), Form 1065 and Form 1120-S filers face a March 15 due date. Their 2026 tie lands on Wednesday, September 16, 2026, and Thursday, September 17, 2026 drops to 179 days. Filing Form 4868 (individuals) or Form 7004 (entities, 5½ or 6 months; see “Assumptions and limits” below) extends the return and keeps all 180 days.

Under 26 CFR 1.1031(k)-1(c)(2) and (c)(3), you must sign a written notice naming each new tract. Give the street address, legal text or clear name (such as “the Mayfair Apartment Building”). Send it before midnight on day 45 to the seller or a neutral party. Neutral parties include a qualified intermediary, escrow agent or title firm. Under 26 CFR 1.1031(k)-1(c)(4), you can list up to 3 tracts of any price. Or you can list more tracts worth at most 200 percent of what you gave up. If you exceed both caps, 26 CFR 1.1031(k)-1(c)(4)(ii) voids the list unless an exception applies. Tracts closed by day 45 still count, or you can close on 95 percent of the list's total price.

Section 1031 deadline and identification formulas

Day 45 (strict) = Transfer date + 45 calendar days (transfer date is Day 0; 26 CFR 1.1031(k)-1(b)(2)(i))
Day 180 (strict) = Transfer date + 180 calendar days (26 CFR 1.1031(k)-1(b)(2)(ii))
Exchange deadline (strict) = min(Day 180 (strict), Unshifted return due date with extensions for the transfer year)
Section 7503 reading = Shift Day 45, Day 180 and the return due date to the next day that is not Saturday, Sunday or a D.C. legal holiday (26 U.S.C. 7503; 26 CFR 301.7503-1(b); D.C. Code 28-2701; 5 U.S.C. 6103(a))
Quantity test (26 CFR 1.1031(k)-1(c)(4)) = (Count ≤ 3) OR (Aggregate identified ≤ 2 × Relinquished) OR (Received ≥ 0.95 × Aggregate identified)

Worked examples

Default case (95-percent rescue and early close): You give up rental land worth $500,000 on Thursday, October 1, 2026 as an April 15 filer with no extension. Day 45 is Sunday, November 15, 2026 (Monday, November 16, 2026 if 26 U.S.C. 7503 moves it). Day 180 is Tuesday, March 30, 2027, ahead of the Thursday, April 15, 2027 return date. The swap window therefore ends on Tuesday, March 30, 2027. You list 4 tracts at $300,000 each ($1,200,000, or 240.00% of $500,000). That exceeds both 3 tracts and the $1,000,000 200-percent cap. Closing on $1,150,000 (95.83%, above the $1,140,000 95-percent floor) saves all $1,150,000. Had you closed on $1,100,000 (91.67%) all after day 45, $0 would count. Suppose one $300,000 tract closed by day 45 and $800,000 closed later. Then $300,000 would still count under 26 CFR 1.1031(k)-1(c)(4)(ii)(A) and $800,000 would fail.

Late-December sale and 26 CFR 1.1031(k)-1(c)(7) cases: Suppose you sell on Tuesday, December 15, 2026 instead. Day 45 is Friday, January 29, 2027 and day 180 is Sunday, June 13, 2027. Without an extension, your Thursday, April 15, 2027 return due date cuts the window to 121 days (59 days short of 180 days). Filing Form 4868 moves the return to Friday, October 15, 2027 and restores Sunday, June 13, 2027. Under the 7503 reading in the weekend and holiday section above, that becomes Monday, June 14, 2027. Next, look at 26 CFR 1.1031(k)-1(c)(7) Examples 4, 5 and 7 for a $100,000 sale on Friday, May 17, 1991. Day 45 is Monday, July 1, 1991 and day 180 is Wednesday, November 13, 1991. Three tracts at $75,000, $100,000 and $125,000 meet the 3-property rule of 26 CFR 1.1031(k)-1(c)(4)(i), and four tracts totaling $180,000 stay within its $200,000 cap. In Example 7, four tracts totaling $310,000 remain after a void phone call and only the $90,000 and $100,000 tracts close — $190,000 here (61.29%, below the $294,500 95-percent floor), so the list fails.

Assumptions and limits

• This tool runs exact date and cent math under 26 U.S.C. 1031(a)(3) and 26 CFR 1.1031(k)-1, which govern alongside IRS filing instructions. Sale dates run from January 1, 2018 (when 26 U.S.C. 1031(a)(1) became real-estate-only; see “Disaster postponements, reverse exchanges and related parties” above) to December 31, 2098. Custom return dates run from 45 days after the transfer to December 31, 2100.
• Under 26 CFR 301.7503-1(b), the 26 U.S.C. 7503 reading skips Saturdays, Sundays and District of Columbia legal holidays, which include those listed in D.C. Code section 28-2701. Juneteenth counts from June 17, 2021, when Pub. L. 117-17 enacted the June 19 federal legal public holiday in 5 U.S.C. 6103(a). IRS Publication 509 (2022) lists observed Friday, June 18, 2021 and Monday, June 20, 2022 as legal holidays. For cross-reference, D.C. Law 24-147 section 133(a) added Juneteenth to section 28-2701 on July 12, 2022. Section 28-2701 also lists D.C. Emancipation Day on April 16 (from April 7, 2006 under D.C. Law 16-91 section 109). It also lists Inauguration Day every fourth year. Under section 28-2701, Saturday holidays other than Inauguration Day move to Friday, and Sunday holidays move to Monday. State holidays outside D.C. and unscheduled office closures are not modeled.
• Under 26 U.S.C. 6081(b), the code text lists a 5-month C-corp extension before 2026 and 6 months from 2026 on. The IRS Form 7004 instructions state: “The automatic extension period for time to file is generally 6 months.” Calendar-year C corporations therefore extend 6 months to October 15 across 2018 to 2098. Under Pub. L. 114-41 section 2006(b)(2) and those instructions, a calendar-year trust or estate (except a bankruptcy estate) gets 5½ months to September 30. The table “How each calendar-year filing schedule affects this transfer” compares all five schedules for your transfer date, and “How the 45-day and 180-day periods work” above lists their due dates and extension forms.
• Under 26 CFR 1.1031(k)-1(c)(4)(i)(B) and (c)(4)(ii), the 200-percent cap prices tracts at the end of day 45 (or expected close for build-to-suit land under paragraph (e)(2)(ii)). The 95-percent floor prices each tract on close or the last swap day, whichever is first. Re-test with close-day prices if values moved after day 45. This page does not check written delivery, tract wording or revocations under paragraph (c)(6). It also does not verify whether received land is “substantially the same property as identified” under paragraph (d)(1), intermediary papers or 26 U.S.C. 7508A disaster notices. If a swap fails or uses a buyer note, see the capital gains tax calculator and installment sale calculator.

These figures are estimates for learning and planning, not financial, tax, legal or investment advice. Terms of use.

What to do before you close and identify

Sign a written swap contract with a qualified intermediary under 26 CFR 1.1031(k)-1(g)(4) and (k) before closing so sale proceeds stay in the safe harbor. Put the strict day-45 and swap cutoffs on your calendar on Day 0. Acting by the strict date satisfies both the strict reading of 26 U.S.C. 1031(a)(3) and the 26 U.S.C. 7503 reading.

Check the table “How each calendar-year filing schedule affects this transfer” on closing day. Without an extension, April 15 filers lose strict days after October 17 (October 18 before a leap year; up to October 21 under 7503). March 15 filers lose strict days after September 16 (September 17 before a leap year; up to September 19 under 7503). Do not file your return before your last purchase closes, and extend under 26 U.S.C. 6081 (forms in “How the 45-day and 180-day periods work” above) to keep all 180 days.

Send your signed written list before midnight on day 45 with each tract's address, legal text or clear name. Save proof of delivery under 26 CFR 1.1031(k)-1(c)(2)–(3). Stay within 3 tracts or 200 percent when you can, or revoke extras in writing by day 45 under paragraph (c)(6). File Form 8824 with your return, and check the IRS penalty and interest calculator if a return runs late.

Questions about 1031 exchange deadlines