The 45-day and 180-day rules, in §1031’s own words

1. The 45-day period, and what missing it actually does

Paragraph (3) of subsection (a) is where both deadlines live, and the first thing to read is its opening words rather than its numbers. It begins "For purposes of this subsection", so its effect is confined to subsection (a) — the nonrecognition rule — and it is drafted as a rule about PROPERTY rather than about the transaction. Property received by the taxpayer "shall be treated as property which is not like-kind property" if either of two things is true.

That is a deeming rule, and the distinction is worth holding on to, because the popular phrasing — "the exchange fails" — is a conclusion rather than what the text says. What the text does is take the property outside the like-kind description that subsection (a)(1) requires. Subsection (a)(1) grants nonrecognition where real property is exchanged solely for real property of like kind; property that (a)(3) has deemed not to be like-kind property no longer answers that description.

Subparagraph (A) is the 45-day rule. The property is deemed not like-kind if it "is not identified as property to be received in the exchange on or before the day which is 45 days after the date on which the taxpayer transfers the property relinquished in the exchange". Three features of that sentence are worth reading slowly. The clock starts on the date the taxpayer transfers the RELINQUISHED property — the disposal side of the exchange, not the acquisition side. The deadline is stated inclusively, "on or before" the 45th day, so the 45th day itself is inside the period. And the requirement stated here is identification and nothing else; the subparagraph does not say identification of how many properties, to whom, or in what form.

The two subparagraphs are joined by "or", so either one is enough on its own to trigger the deeming. Identifying property on time does not help if it is received too late, and receiving it quickly does not help if it was never identified within the period.

2. The 180-day period, and the date that can arrive before it

Subparagraph (B) is the receipt deadline, and it is not a single date. Property is deemed not like-kind if it "is received after the earlier of" two days: clause (i), the day which is 180 days after the date the taxpayer transfers the relinquished property, and clause (ii), the due date — "determined with regard to extension" — for the transferor’s return of the tax imposed by this chapter for the taxable year in which the transfer of the relinquished property occurs.

Clause (i) runs from the same event subparagraph (A) does. That is the point most often lost in summary: the 45-day period is not a first phase followed by a 180-day second phase. Both are measured from the transfer of the relinquished property, so the receipt period is 135 days longer than the identification period, and the identification period sits inside it.

Clause (ii) is a cap, and its date is not on this page. It is the due date of the transferor’s own return for the year of the transfer, which depends on who the taxpayer is and on Code sections this article does not quote — and it moves if the return is extended, because the statute says the date is determined with regard to extension. What the words do establish is the direction of the rule: because subparagraph (B) takes the EARLIER of the two, a transfer that happens late in a tax year can leave fewer than 180 days, since the return deadline for that year may arrive before the 180th day does.

Read together, the paragraph produces one calendar with two marks on it and a possible third that belongs to the taxpayer’s return rather than to the exchange.

3. What subsection (a) requires before a deadline matters

The deadlines only ever operate on an exchange that is otherwise within subsection (a), so paragraph (1) is the description everything else hangs from. It grants nonrecognition of gain OR loss — both words are in the text, so the paragraph withholds a loss on the same terms as it withholds a gain — on the exchange of real property held for productive use in a trade or business or for investment, if such real property is exchanged solely for real property of like kind which is to be held either for productive use in a trade or business or for investment.

There are two holding-purpose requirements in that sentence and not one. The property given up is described as held for productive use in a trade or business or for investment; the property received is described as "which is to be held" for one of the same two purposes. The first looks backwards at how the property has been used, the second forwards at what is to be done with the replacement.

The word "solely" is doing a great deal of work, and it is the hinge for the next section of this page. Paragraph (1) grants nonrecognition where the exchange is solely for like-kind real property. Where it is not solely that — where money or other property also changes hands — subsections (b) and (c) pick the case up, and they do it by asking what WOULD have been within subsection (a) but for that fact.

Paragraph (2) then removes a category outright: the subsection does not apply to any exchange of real property held primarily for sale. It is one sentence, it has no conditions attached, and its subject is the holding purpose rather than the property type.

4. When it is not solely in kind: subsections (b), (c) and (d)

Subsections (b) and (c) are a near-matched pair, and both are written as counterfactuals rather than as exceptions. Each begins: if an exchange WOULD be within the provisions of subsection (a) — or of section 1035(a), 1036(a) or 1037(a), three neighbouring nonrecognition provisions this page does not quote — but for the fact that what was received consists not only of the permitted property but also of other property or money, then a rule applies. The two are not word-for-word identical, and the difference is visible in the quotes below: (b) describes property permitted to be received without the recognition of gain, while (c) describes property permitted to be received without the recognition of gain or loss.

For gain, subsection (b) is a ceiling. The gain, if any, to the recipient "shall be recognized, but in an amount not in excess of the sum of such money and the fair market value of such other property". Two things are observable in that wording. It is phrased as a limit — "not in excess of" — rather than as an amount to be recognised outright, and the words "if any" sit in front of it. And what sets the limit is the money plus the fair market value of the other property received, not the size of the deal. How the limit interacts with the gain a taxpayer has actually realised is a computation this page does not perform.

For loss, subsection (c) is flat: where it applies, "no loss from the exchange shall be recognized". The symmetry of (b) and (c) is only apparent. Receiving money or other property can force some gain to be recognised, but it never lets a loss out.

Subsection (d) is the basis rule, and it is what makes the whole arrangement a deferral rather than a forgiveness. Basis in the acquired property is the same as that of the property exchanged, decreased by money received and increased by gain or decreased by loss recognised on the exchange. A second sentence allocates that basis where part of what was received was other property, assigning the other property an amount equivalent to its fair market value at the date of the exchange. A third sentence addresses debt: where another party to the exchange assumed a liability of the taxpayer, that assumption "shall be considered as money received by the taxpayer on the exchange" — which routes it into the same machinery as cash in subsections (b) and (d).

5. A second clock: the two-year rule for related persons

This is the longest section on the page and the furthest from a scheduling question, so it is worth saying why it is here. Section 7 below makes a series of claims about what §1031 does NOT say, and those claims hold only if the whole section is on the page — a phrase cannot be shown to be absent from a document that has been quoted in part. Subsections (f) and (g) are eighteen of the thirty units. They are also the part of the section most likely to matter to a client who is exchanging with somebody they know.

Subsection (f) adds a period that runs long after the exchange has closed, and it is measured differently from the two in subsection (a). Paragraph (1) sets out three conditions joined by "and": a taxpayer exchanges property with a related person; there is nonrecognition to the taxpayer under the section, determined without regard to this subsection; and before the date 2 years after the date of the LAST TRANSFER which was part of the exchange, either the related person disposes of the property or the taxpayer disposes of the like-kind property received from them.

Where all three hold, the concluding sentence of the paragraph withdraws the result: there shall be no nonrecognition to the taxpayer with respect to the exchange, and any gain or loss recognised by reason of the subsection is taken into account as of the date the disposition occurs rather than the date of the exchange. So the consequence is retrospective in substance and prospective in timing.

Paragraph (2) then takes three dispositions out of the count: one after the earlier of the death of the taxpayer or the death of the related person; one in a compulsory or involuntary conversion within the meaning of section 1033, if the exchange occurred before the threat or imminence of that conversion; and one where it is established to the satisfaction of the Secretary that neither the exchange nor the disposition had as one of its principal purposes the avoidance of Federal income tax.

"Related person" is not defined in §1031’s own words. Paragraph (3) borrows it: any person bearing a relationship to the taxpayer described in section 267(b) or 707(b)(1) — two sections this page does not quote. Paragraph (4) is an anti-avoidance rule with a broader subject than the rest of the subsection: the SECTION does not apply to any exchange which is part of a transaction, or series of transactions, structured to avoid the purposes of the subsection.

Subsection (g) then suspends the two-year period. Where the holder’s risk of loss on the property is substantially diminished — by the holding of a put, by another person holding a right to acquire the property, or by a short sale or any other transaction — the running of the period set forth in subsection (f)(1)(C) is suspended for as long as that is so. The third item, "any other transaction", is open-ended on its face.

6. Two edges of the section: partnership interests and foreign property

Two subsections mark an edge of the section rather than a step in its machinery, and each is a single sentence.

Subsection (e) addresses a narrow kind of partnership. Where a partnership has in effect a valid election under section 761(a) to be excluded from the application of all of subchapter K, an interest in it is treated for purposes of this section as an interest in each of the assets of the partnership, and not as an interest in a partnership. The subsection speaks only about partnerships that have made that election; it says nothing either way about any other partnership interest.

Subsection (h) draws a geographic line: real property located in the United States and real property located outside the United States are not property of a like kind. Because like-kind is the description subsection (a)(1) is built on, this puts a cross-border pairing outside (a)(1) by definition rather than by a condition that might be satisfied.

7. Words the section does not contain

Everything above is the whole of §1031, which makes it possible to say something about the section that is ordinarily unsafe to claim about any document: what is not in it. Each of the following can be checked against the thirty quotations on this page, and that is the point of quoting them all.

The section does not contain the phrases "qualified intermediary", "exchange accommodator", "reverse exchange", "build-to-suit" or "boot". None of those five appears anywhere in its text. A reader who has met them in an article about §1031 has met them from somewhere other than §1031, and this page does not say where.

The section does not say how many replacement properties may be identified, or in what form, or to whom. Subparagraph (a)(3)(A) requires that the property be "identified as property to be received in the exchange" on or before the 45th day, and stops there. No count of replacement properties appears anywhere in the section, and neither does any percentage. Its figures are 45, 180, the two years in subsection (f)(1)(C), and cross-references to other Code sections.

The section states no minimum holding period in years. Paragraph (a)(1) describes purpose ("held for productive use in a trade or business or for investment"), paragraph (a)(2) excludes property held primarily for sale, and the sole period expressed in years anywhere in the section is the two-year window in subsection (f)(1)(C), which is about a related person’s later disposition rather than about how long anything must be held first.

The section does not say whether its days are calendar days or business days. Both deadlines are expressed as "the day which is 45 days after" and "the day which is 180 days after" a date, and no definition of "day" appears anywhere in the section. Anyone arriving here from a rule that does define its days — the companion article on the Closing Disclosure quotes one — should notice that this section supplies no such definition at all, in either direction.

And the section says nothing about a home. There is no reference in it to a principal residence, and the provision that addresses gain on the sale of one is a different section of the Code that this page neither cites nor quotes.

One thing this list is not. A phrase being absent from §1031 is a fact about §1031, and it is not a statement that the thing the phrase names is unnecessary, optional, or without legal effect somewhere else. The Treasury regulation under this section is 26 C.F.R. §1.1031(k)-1, not one word of it is quoted here, and no sentence on this page says what any part of it provides or does not require. A reader who took the absence of "qualified intermediary" from the statute as an answer to whether an exchange needs one would be drawing a conclusion this page does not support and has not looked into.

So the locator is a locator and nothing more. A statement that is true of the statute alone is not automatically true once the regulation is read alongside it.

Where each of the opening questions lands in the text

This page opened with three things that reach an agent rather than a tax adviser. What follows is not an answer to any of them — it is where each one lands in the text, so the reading starts in the right place instead of at a search result.

The seller who wants to roll a gain into another building runs first into subsection (a)(1), and into two separate holding-purpose descriptions in it: how the relinquished property has been held, and what the replacement "is to be held" for. Then into (a)(2), which removes real property held primarily for sale from the subsection altogether.

The closing that gets pushed runs into (a)(3)(B), and specifically into the words "the earlier of". Whether a delay matters at all depends on which of the two dates in that subparagraph is the earlier one, and clause (ii) makes the second of them a fact about the taxpayer’s return rather than about the transaction.

The client asking how many properties they may name runs into (a)(3)(A) and finds that the question is not answered there — the subparagraph asks for identification and says nothing about a count. Where it IS answered is outside this page. The Treasury regulation under this section is 26 C.F.R. §1.1031(k)-1, and this page neither quotes it nor says what it provides.

None of the three is resolved by knowing where it lands. What changes is that the reading starts at the provision the question actually turns on, rather than at whichever page ranked that morning.

How to check the completeness claim yourself

The whole page rests on one claim — that §1031 is quoted here end to end — and section 7 rests on it twice over, because a phrase cannot be shown to be missing from a document quoted in part. So the claim is stated as arithmetic anyone can redo against the source. Subsection (a) breaks into seven units — paragraphs (1) and (2), then paragraph (3)’s chapeau, subparagraph (A), subparagraph (B)’s chapeau and its two clauses. Subsections (b), (c), (d) and (e) are one paragraph each. Subsection (f) is thirteen: paragraph (1)’s chapeau, three subparagraphs, two clauses under (C) and a concluding sentence, then paragraph (2)’s chapeau and three subparagraphs, then paragraphs (3) and (4). Subsection (g) is five, and subsection (h) is one. Seven plus four plus thirteen plus five plus one is thirty; there are thirty quotations above; and every line on the source page that is not reproduced in one of them is a catchline, which OLRC prints on its own line above the text it heads.

Then check the second thing, which is the publisher. Every citation on this page resolves to one URL at the Office of the Law Revision Counsel, and the choice is deliberate: a numbered edition of the Code carries a year in its title and never changes after that year, so a quote taken from one keeps testing clean long after Congress has moved the words. §1031 is a section that has moved — a 2017 amendment is what left its operative grant speaking of real property — and the version above is the one OLRC was serving on the date beside each quote.

What the completeness claim does NOT extend to is anything outside §1031, and this section borrows heavily. Subsections (b), (c) and (d) each name sections 1035(a), 1036(a) and 1037(a). (d) turns on section 357(d) for when a liability counts as assumed. (f)(2)(B) turns on section 1033 for what an involuntary conversion is, and (f)(3) takes its whole definition of a related person from sections 267(b) and 707(b)(1). Not one of those seven is quoted here, so a reading of the words above can be undone by a section this page never opened.

Two further boundaries. This is federal income tax, and what a state does with the same gain is a separate question under a separate statute this page does not reach. And the section is the first of three layers — statute, Treasury regulation, and how courts have read both — of which only the first is here.

Real Deal Pro, Inc. builds transaction software. It is not a brokerage, a title company, a tax adviser or a law firm, and it has no view on any particular exchange. The people who do are a CPA or a tax attorney who handles them.

Wrapping up

Section 1031 grants nonrecognition of gain or loss where real property held for productive use in a trade or business or for investment is exchanged solely for real property of like kind that is to be held for one of those same purposes, and it removes real property held primarily for sale from that subsection entirely. Paragraph (a)(3) then attaches the deadlines, drafted as a rule deeming property not to be like-kind property rather than as a rule voiding a transaction.

Both deadlines are measured from one event — the day the taxpayer transfers the relinquished property. Identification has to have happened on or before the 45th day after it. Receipt has to happen on or before the earlier of the 180th day after it and the due date, with extensions, of the transferor’s return for the year the transfer falls in. The second of those is a date that belongs to the return rather than to the exchange, and it is why a transfer late in a tax year is not simply a transfer with 180 days after it.

The rest of the section says what happens when money or other property is also received (gain recognised up to that amount, no loss recognised, basis adjusted and allocated), attaches a two-year rule to exchanges with a related person that a diminution of risk can suspend, treats an interest in a section 761(a)-electing partnership as an interest in its assets, and says that United States and non-United States real property are not of a like kind.

And the section is quieter than its reputation. It fixes two periods and a cap, describes what may be exchanged for what, and says what happens when money joins the deal. The identification mechanics, the intermediary and the counting rules are not in §1031. Knowing which half is which is the part of this an agent can actually carry into a scheduling conversation.

Next step

The block in section 2 describes the closing-date rule; the features section shows the checklists a workspace can hang that rule on and the calendar where the resulting due dates appear.

Per-stage task checklists, and the calendar their due dates land on

Related reading

• How the Closing Disclosure three-day rule works, and what the creditor needs from you

  The other federal deadline an agent can move by moving a closing date

• What makes a real estate agent a statutory nonemployee

  The federal definition that decides whether an agent is an employee for tax purposes

Sources

Every quotation above is taken from the documents below, on the date shown; the explanation around each quote is ours. Statutes are amended and uniform acts are revised — check the current text before relying on any of it.

1. [1] 26 U.S.C. §1031 — Exchange of real property held for productive use or investment — Office of the Law Revision Counsel, U.S. House of Representatives, uscode.house.gov/view.xhtml, read August 20, 2026