The short answer
Sell first, in a forward exchange, when your property will be easy to sell and the replacement is the uncertain part, and protect the purchase side with backups on your 45-day list, including DST interests that can close within days. Buy first, in a reverse exchange, only when the replacement is the scarce asset and you are confident your own property will sell within 180 days, because the safe harbor flips the pressure onto the sale. A reverse exchange also needs the purchase money before you have sale proceeds, a lender willing to work with a parking entity, and more fees. Run the comparison with your CPA and intermediary before you sign either contract.
At a glance
| Forward clocks | Identify replacement in 45 days, close within 180 days of the sale |
|---|---|
| Reverse safe harbor | Parking arrangement under Rev. Proc. 2000-37 with an exchange accommodation titleholder |
| Reverse clocks | Agreement within 5 business days; identify relinquished property in 45 days; finish in 180 days |
| Financing in a reverse | You may lend to, advance funds to or guarantee the titleholder's loan |
| Own property | Cannot park replacement you owned in the prior 180 days |
| Third path | A forward exchange with DST interests as backup identifications |
The order decides which deadline you are exposed to
In a forward exchange you sell first. Under Reg. section 1.1031(k)-1, you identify replacement property within 45 days and receive it by the earlier of 180 days or your return's due date, with extensions. The sale risk is gone on day one; the purchase risk runs the whole period.
In a reverse exchange you buy first. An exchange accommodation titleholder holds title to the replacement, or to the property you are selling, under a qualified exchange accommodation arrangement. Rev. Proc. 2000-37 requires the written agreement within five business days of the titleholder taking title, identification of the property to be sold within 45 days, and completion within 180 days. The purchase risk is gone on day one; the sale risk runs the whole period.
So the question is which side of your deal is harder in today's market. Our reverse exchange guide covers the mechanics in depth; this page is about the choice.
When a forward exchange is the safer order
If buyers for your property are scarce, selling first removes the risk that matters most. A reverse exchange in that market leaves you holding two properties through a titleholder while the 180 days run, and if the sale misses, the parking arrangement falls outside the safe harbor.
Forward exchanges also cost less and involve fewer parties: a qualified intermediary holds the proceeds under the Reg. section 1.1031(k)-1(g) safe harbor, and you buy with the money from your sale rather than raising it in advance.
Timing inside the forward order still matters. Start the identification work before the sale closes, line up financing for the replacement in advance, and know which of your backups can close fastest if the first choice fails late. The 45 days run from the transfer of the relinquished property whether or not you have started looking.
The weak point is the purchase. Name backups: three properties of any value, or more under the 200% rule, as our answer on identifying replacement property explains.
When a reverse exchange earns its cost
A reverse exchange makes sense when the replacement is unique or contested, such as the building next to yours or an off-market property with a firm closing date, and your own property is liquid enough to sell within 180 days.
You have to fund the purchase before you have proceeds. Rev. Proc. 2000-37 lets you or a related person lend or advance funds to the titleholder, guarantee its loan, lease the property from it and manage it, without breaking the safe harbor. Lenders must still be willing to lend to the titleholder's entity on those terms, which can slow closing; ask early.
Two limits matter. Rev. Proc. 2004-51 bars parking replacement property you owned within the 180 days before the titleholder took title. And our answer on buying a DST before the property sells explains why a reverse exchange into a trust interest is rarely workable.
Budget for more than the titleholder's fee. A reverse exchange usually means two sets of closing costs in quick succession, carrying costs on the parked property, and interest on the loan that funds it until your sale closes. Get written quotes from the intermediary and lender and compare them with the tax you would defer.
A hypothetical comparison: the same deal run in each order
Hypothetical, round numbers. You own a $1,200,000 rental free and clear and want a $1,500,000 building that will not wait.
Forward: you list first. If the rental sells in six weeks, you have the money, but the building may be gone, and your list needs two backups. If none closes by day 180, the gain is taxed.
Reverse: a titleholder buys the building now with $1,500,000 that you raise through a loan to the titleholder you guarantee and your own cash. You then have 180 days to sell the rental. If it sells, the titleholder conveys the building to you as replacement and the proceeds repay the loan. If it does not, the arrangement falls outside the safe harbor, the building cannot count as replacement under it, and the rental's eventual sale is taxed unless you start a new exchange. Run your own numbers with your CPA.
The third path: a forward exchange with DST interests as the backup
Many owners use a reverse exchange to escape the risk of finding nothing in 45 days. A cheaper hedge keeps the forward order and adds DST interests to the identification list. Interests in existing trusts are available on the offering's timetable and, by our own experience with traditional DSTs, often close within 3 to 5 business days.
If the target building closes, the trusts are simply not bought. If it falls through after day 45, the trusts on the list let you complete the exchange. Our DST backup strategy guide covers how to size them.
Related questions
Is a reverse exchange riskier than a forward one?
It moves the risk rather than removing it. A forward exchange risks the purchase; a reverse exchange risks the sale, plus the cost of funding the purchase in advance and the titleholder's fees.
Can I live with the 180 days if my property needs repairs to sell?
Only if the repairs and the sale fit inside 180 days from the titleholder's acquisition. Rev. Proc. 2000-37 counts the combined holding period, and there is no extension for market conditions.
Can my lender lend directly to me in a reverse exchange?
The titleholder holds title, so the loan usually runs to its entity with your guarantee, which Rev. Proc. 2000-37 allows. Whether a lender will do that is a business question to settle early.
Can I park a property I already own and build on it?
Not under the safe harbor. Rev. Proc. 2004-51 excludes replacement property you owned within the prior 180 days, and an exchange of land you own for improvements on it is not like-kind.
Should I add DSTs to my list even if I expect the building to close?
That is their purpose as a backup. Keep the list within the three-property or 200% limits, and see DST backup strategy for sizing.
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.