The short answer
Exchange-first and exchange-last are the two ways to park property in a reverse exchange: in exchange-last the exchange accommodation titleholder holds the replacement property until your old property sells, and in exchange-first it buys the replacement, swaps it to you at once for your relinquished property, and then holds the relinquished property until it sells. Both structures are described in Rev. Proc. 2000-37, which supplies the safe harbor for either, though the two labels are market shorthand rather than the procedure's words. The choice mostly turns on which property can be financed or held in the titleholder's name for up to 180 days.
At a glance
| Exchange-last parks | The replacement property, until the relinquished property is sold |
|---|---|
| Exchange-first parks | The relinquished property, after an immediate swap |
| Identification | Relinquished property identified within 45 days of the parking |
| Time limit | 180 days, counting the combined time both properties are parked |
Both formats come from the same paragraph of Rev. Proc. 2000-37.
Section 2.05 of Rev. Proc. 2000-37 describes parking transactions that park the desired replacement property with an accommodation party until the taxpayer arranges the transfer of the relinquished property, and other situations in which the accommodation party acquires the replacement property and immediately exchanges it with the taxpayer for the relinquished property, then holds the relinquished property until it is sold. The first is exchange-last; the second is exchange-first.
Either way the property must be held in a qualified exchange accommodation arrangement under section 4.02: the titleholder holds qualified indicia of ownership, a written agreement is signed within five business days, the relinquished property is identified within 45 days, the property is transferred within 180 days, and the combined time both properties are held in the arrangement does not exceed 180 days. Rev. Proc. 2004-51 excludes replacement property you owned within the 180 days before the parking.
In a hypothetical purchase, the format decides whose name is on the new loan.
Hypothetically, you must close on a $2,000,000 warehouse before your office building has a buyer. In exchange-last, the titleholder takes title to the warehouse, which section 4.02(1) allows it to hold through a disregarded single-member entity, financed with a loan or advance that you may guarantee or fund, and leases it to you. When the office building sells through a qualified intermediary, the proceeds buy the warehouse from the titleholder.
In exchange-first, the titleholder buys the warehouse and conveys it to you immediately in exchange for your office building, which it then holds and sells within the 180 days. The warehouse loan can sit in your own name, but the titleholder must hold, and carry, your old building. Ask your lender which format it will finance before you sign, and run your own numbers with your CPA.
It bites in the permitted-arrangement rules and in the clock that covers both properties.
Section 4.03 allows the arrangements that make either format work: you or a disqualified person may guarantee the titleholder's debt, lend it money, lease or manage the property, and agree puts and calls with the titleholder for up to 185 days. Those are the levers that keep risk with you while the titleholder holds title.
The 180-day ceiling in section 4.02(6) runs on the combined parking time, so a sale that drags past day 180 takes the arrangement outside the safe harbor. See the reverse exchange guide, buying a DST before your property sells, and the general safe harbor concept.
Related questions
Can the accommodation titleholder also be my qualified intermediary?
Yes. Section 4.03(1) of Rev. Proc. 2000-37 allows a titleholder that meets the qualified intermediary safe harbor to enter into an exchange agreement with you to serve as intermediary in the simultaneous or deferred exchange of the property.
Who can be the accommodation titleholder?
Someone other than you or a disqualified person who is subject to federal income tax, or, if it is a partnership or S corporation, more than 90 percent owned by taxpaying partners or shareholders, under section 4.02(1).
What if the old property does not sell within 180 days?
The safe harbor no longer applies, and ownership of the parked property is decided on the facts without it, under section 3.04 of the procedure. See what to do after a failed exchange.
Sources
Checked against these publications on September 30, 2026. Rules and figures change; confirm the current version with your CPA or attorney before you act. This page is general information, not tax or legal advice.