Improvement (Build-to-Suit) 1031 Exchanges: Rules and Timelines
An improvement exchange, also called a build-to-suit or construction exchange, uses your 1031 exchange proceeds to build on or improve the replacement property before you take title to it. An exchange accommodation titleholder holds title while the work is done under the safe harbor in Rev. Proc. 2000-37, and only the improvements in place when the property is transferred to you, within the exchange period, count as like-kind property. Anything built after you receive the property does not count, which is why the 180-day clock drives every decision.
Investors use this structure when the replacement property is worth less than what they sold until money goes into it: a lot that needs a house or ADU, a vineyard that needs a replant, or a commercial building that needs tenant improvements. This page explains the rules, how value is counted, the limits on building on land you already own, and why permit timelines in Sonoma and Napa make planning essential. It is part of our California 1031 exchange guide.
The core rule: only what exists when you receive it counts
The Treasury regulation on deferred exchanges, 26 CFR 1.1031(k)-1(e), allows replacement property that is not yet built when you identify it. Three parts of that rule shape an improvement exchange:
- Identification. For land with construction pending, you identify the land by legal description and give as much detail about the planned construction as is practicable when you identify it.
- Receipt. Real property that is not finished when you receive it can still count as substantially the same as what you identified, but only to the extent it would have qualified if finished and only to the extent it is real property under local law at that time.
- No credit for later work. Under paragraph (e)(4), production that happens after you receive the property is not treated as receipt of like-kind property. Transferring your relinquished property in exchange for services, including construction services, is also outside Section 1031.
The regulation’s own example makes the point. A taxpayer receives replacement real property that is 20% complete; the exchange covers the land and the completed 20% of construction, and the construction finished afterward does not count.
So in an improvement exchange you never take title to the land and then build. Someone else owns it while the money is spent, and you receive land plus completed work at the end.
How the parking arrangement works
Rev. Proc. 2000-37 is the same safe harbor used for reverse exchanges. An exchange accommodation titleholder, often through a single-member LLC, holds title to the replacement property in a qualified exchange accommodation arrangement while improvements are made. The written agreement, signed within five business days after the titleholder takes title, and the 180-day limit apply as they do in a reverse exchange, while the deferred exchange rules govern how you identify the replacement property.
Section 4.03 of the revenue procedure lists arrangements that do not disqualify the safe harbor, several of which make construction possible:
- You may guarantee some or all of the titleholder’s obligations.
- You may lend or advance funds to the titleholder, or guarantee a loan to it.
- The titleholder may lease the property to you.
- You may manage the property, supervise the improvements, act as contractor or otherwise provide services to the titleholder for the property.
The revenue procedure took effect for titleholders that acquired qualified indicia of ownership on or after September 15, 2000. In a forward improvement exchange, your qualified intermediary holds the sale proceeds, which can be advanced to the titleholder for the purchase and the construction draws.
The two clocks
A forward improvement exchange runs on two overlapping deadlines, and the earlier one controls.
| Clock | Starts | Ends |
|---|---|---|
| Deferred exchange period (Treas. Reg. 1.1031(k)-1(b)) | The day you transfer the relinquished property | Midnight on the earlier of the 180th day or the due date, with extensions, of your tax return for that year |
| Identification period | The same day | Day 45: identify the replacement land and planned improvements |
| Parking arrangement (Rev. Proc. 2000-37) | The day the titleholder acquires the replacement property | No later than 180 days after that acquisition, the property must be transferred to you |
If the titleholder buys the replacement land 30 days after your sale closes, the deferred exchange period still ends on day 180 from the sale, so you have about 150 days of construction, not 180. Map both sets of dates with our 1031 deadline calculator, and read our identification rules guide for the 45-day requirements.
When you apply the 200% and incidental property rules to property to be produced, the regulation values it at its estimated fair market value on the date you expect to receive it. Identify improvements you can realistically finish, because the value you identify and the value you receive need to line up.
Counting value at the end
To defer all of the gain, the property you receive, land plus completed improvements, generally needs to be worth at least as much as the property you sold, with all of the exchange proceeds spent on it. Money still held at the end of the period, or spent on work that is not in place when you take title, does not become like-kind property. Any leftover cash that comes back to you is boot, taxable to the extent of your gain, as our guide to boot and partial exchanges shows.
Deposits paid to contractors for work not yet performed, materials sitting on site and design work for a later phase are the usual problem items. Ask your tax adviser how each would be treated before day 180.
Building on land you already own
A common idea is to sell a rental and use the proceeds to build on a lot you already own. Rev. Proc. 2004-51 closed the simplest version of that: it modified Rev. Proc. 2000-37 so that the safe harbor does not apply to replacement property held by a titleholder if you owned that property within the 180 days ending on the date the titleholder acquires it.
You cannot sell your own lot to an accommodator and then exchange back into it with a new house on it under the safe harbor. Structures involving land owned by you or a related party are outside the safe harbor and need specific advice from a tax attorney or CPA before any money moves.
Can the work be finished in time in Sonoma and Napa?
This is where most improvement exchanges succeed or fail. The 180 days must cover permits, contractor scheduling and construction, and local permitting is often the longest piece.
ADUs and new homes
California law requires a local agency to approve or deny a complete ADU application within 60 days when there is an existing single-family or multifamily dwelling on the lot, or the application is deemed approved (Government Code section 66317). The clock runs from a complete application and pauses if you ask for a delay. If the ADU is submitted together with an application for a new dwelling, the agency may hold the ADU decision until it acts on the dwelling.
Sixty days for approval leaves little time to build, so in practice an ADU exchange usually needs plans drawn and the application filed before the titleholder even acquires the property. Sonoma County’s ADU rules and rural constraints such as septic and wells are covered in our guide to land, building lots and ADUs in Sonoma County; the investment side is in our ADU investment guide.
Vineyard development and replants
Vineyard work runs on a longer calendar. Our guide to vineyard development and replanting explains that site studies and county permits come first, then ground preparation and planting, with three growing seasons before a new vineyard leaves California’s property-tax exemption. Only the portion completed before you take title counts, so a full replant rarely fits inside one exchange.
Smaller scopes can: irrigation repairs, a well pump, fencing or trellis work that is permitted, contracted and finished in time. For the purchase side of farmland exchanges, see 1031 exchanges for vineyards and ranch land.
Commercial tenant improvements
Interior build-outs for a new tenant can fit the window when plans are approved and the contractor is ready. If a tenant improvement allowance is part of the lease, coordinate who pays for what; our guide to tenant improvement allowances covers lease terms.
Financing, costs and California points
Construction usually needs more money than the exchange proceeds, and lenders must be willing to lend to the titleholder’s LLC with your guarantee, as Rev. Proc. 2000-37 allows. Get a lender’s written agreement to that structure before you sign with the titleholder. Diamond may refer you to partners we work with; you’re free to choose any provider.
Expect titleholder and intermediary fees, entity setup, construction loan costs, builder’s risk insurance and carrying costs, and get written quotes. California adopts the federal rules on gain or loss from property dispositions under Revenue and Taxation Code section 18031, so a valid exchange also defers state tax. If the property you sell is in California and the replacement is in another state, see our California clawback guide.
This is general information, not legal or tax advice; talk to a CPA or California tax adviser, and a real estate attorney, before you commit to an improvement exchange.
Planning an improvement exchange: the steps
- Confirm the scope can be finished. Get permit timelines from the county or city and a written construction schedule from the contractor before you list the property you are selling.
- File early. Prepare plans and, where possible, submit the permit application before the titleholder acquires the property.
- Line up the parties. Choose a qualified intermediary and titleholder, and confirm the lender will lend to the titleholder’s LLC.
- Identify precisely. By day 45, identify the land by legal description and describe the improvements in as much detail as practicable.
- Track completed value. Keep draw requests, lien releases and inspection sign-offs, so you can document what was in place on the transfer date.
- Close before the earlier deadline. Have the titleholder deed the property to you before the exchange period or the 180-day parking limit ends, whichever comes first.
Questions people ask
What is a 1031 improvement exchange?
An exchange in which an exchange accommodation titleholder holds the replacement property while your exchange funds pay for improvements, then transfers the improved property to you within the exchange period. Only improvements in place at that transfer count as like-kind property.
Do the improvements have to be finished within 180 days?
They don’t have to be finished, but only the work completed when you receive the property counts. Construction after you take title is not treated as like-kind property under Treas. Reg. 1.1031(k)-1(e)(4).
Can I use a 1031 exchange to build on land I already own?
Not within the safe harbor, which Rev. Proc. 2004-51 made unavailable for replacement property you held at any point in the 180 days before the titleholder took title. Any other structure needs specific tax advice.
Can I be my own contractor in an improvement exchange?
Rev. Proc. 2000-37 allows you to supervise improvements, act as contractor or provide other services to the titleholder for the property without losing the safe harbor.
How do I identify property that hasn’t been built yet?
Identify the land by legal description and describe the planned construction in as much detail as is practicable at the time. For the 200% and incidental property rules, its value is the estimated fair market value on the date you expect to receive it.
Can I build an ADU with 1031 exchange funds?
Yes, if the titleholder holds the property during construction and the ADU work is in place when it is transferred to you. With a 60-day state deadline for permit decisions on complete ADU applications, plans usually need to be ready before the exchange starts.
If you are weighing a replacement property that needs work, we can help you test the timeline against permits and the market before you commit, and work alongside your intermediary, lender and CPA. Learn more about our investor services or get in touch to discuss a property.
Sources & notes
- IRS: Internal Revenue Bulletin 2000-40, Rev. Proc. 2000-37
- IRS: Internal Revenue Bulletin 2004-33, Rev. Proc. 2004-51
- Cornell Legal Information Institute: 26 CFR 1.1031(k)-1, deferred exchanges
- California Public Law: Government Code section 66317 (ADU permit timing)
- California Public Law: Revenue and Taxation Code section 18031
Last reviewed October 2026 by Matthew Martinez.
