California to Idaho: The Clawback Meets a Tax State
Idaho is the outlier. It taxes income, which puts two states with a plausible claim on the same dollars. One important question here has no settled answer.
Most California investors who exchange out of state land in Nevada or Texas, where there is no state income tax and the only open question is what California does later. Idaho is different. Idaho taxes income. That puts two states with a plausible claim on the same dollars, and the mechanism that normally prevents that from becoming double tax may not fit this fact pattern.
So here is the honest headline: on a California to Idaho exchange, one important question has no settled answer. Everything else on this page is settled, sourced, and straightforward. This page tells you which is which.
Where Each Piece Stands
| Point | Where it stands |
|---|---|
| Federal 1031 into another state | Fully allowed. Nothing in federal law requires the replacement property to sit in the same state. |
| California’s claim on your gain | Deferred, not erased. The California-source gain keeps its California character. |
| FTB Form 3840 | Filed the year of the exchange and every year after, until the deferred gain is recognized. |
| Idaho income tax | Flat 5.3%, capital gains included. |
| Idaho capital gains deduction | Up to 60%, but only on qualifying Idaho property. It does nothing for the California gain. |
| Credit for the California tax on your Idaho return | Unsettled. No Idaho guidance on point. Read section 4 before you sign anything. |
Deferred, Not Erased
Section 1031 lets you sell investment or business real property and buy replacement real property without paying capital gains tax at the time of sale. Your old basis carries forward.
- 45 days from your closing to identify replacement property in writing.
- 180 days from that closing, or your return due date with extensions, whichever comes first, to close on the replacement.
- You cannot touch the money. A Qualified Intermediary holds the proceeds.
- You report the exchange on IRS Form 8824.
- Since the 2017 tax law, only real property qualifies. California adopted the same real-property-only limit beginning January 1, 2025.
The IRS does not care which state line you cross. California does. Full walkthrough on the 1031 exchange hub. (IRS FS-2008-18 | FTB, Reporting Like-Kind Exchanges)
California Lets You Defer. It Does Not Let You Escape.
Assembly Bill 92 (2013) added R&TC §18032 and §24953, effective for exchanges on or after January 1, 2014. The rule is short to state and long to live with.
- The gain keeps its California source. When California real property goes out of state in a 1031 exchange, the deferred gain does not become Idaho income because the money now sits in a Boise building.
- Residence is irrelevant. The Form 3840 instructions apply the filing requirement to all taxpayers who conduct an IRC Section 1031 exchange, regardless of residence status or commercial domicile. Moving to Idaho changes nothing. Never having lived in California changes nothing.
- Form 3840 is annual and open-ended. File it for the year of the exchange and for each subsequent taxable year, generally until the California-sourced deferred gain or loss is recognized. Attach it to your California return, or file it standalone if you have no other California filing requirement. Hold the Idaho property thirty years, file for thirty years.
- Stop filing and California estimates. If you fail to file the 3840 and fail to file a return, the FTB may estimate net income and assess tax plus penalties and interest. It has run active compliance mailings on this exact form, with 30-day follow-up letters and referral to the Audit Division.
- Withholding at the California closing. California sales normally carry 3 1/3% withholding, but a like-kind exchange is exempt. Boot over $1,500 is still subject to withholding. Get the exemption documented with escrow and your QI before closing.
For the full treatment, read California’s 1031 Clawback Rule and FTB Form 3840: What It Is and How to File It. (2025 Form 3840 Instructions)
The Bill Comes Due on Recognition
Form 3840 is an information return. It costs you nothing. The tax comes due when the deferred gain is recognized, which usually means one of these.
- You sell the Idaho property in a taxable sale. This is the main event.
- You exchange again but pull cash out or reduce debt, so part of the gain is recognized as boot.
- You do something else that ends the deferral. Ask your CPA before you get creative with title or entity structure.
The Publication 1100 example
This is the piece most competing pages skip, and it is the primary source that settles whether California can reach an out-of-state sale. In FTB Publication 1100, the FTB works an example in which a taxpayer exchanges California property for out-of-state property, later sells the replacement, and concludes the deferred gain has a source in California and is taxable by California. The same example caps the taxable amount at the lesser of the deferred gain or the gain recognized on the disposition. (FTB Pub. 1100)
- Defer $500,000 of California gain, roll it into Idaho, later sell the Idaho property at a $200,000 gain? California’s claim is limited by the gain you actually recognized. California does not get to tax gain that never materialized.
- The FTB’s worked example uses Texas facts. The sourcing principle is the same for Idaho, but the arithmetic on your deal turns on basis, depreciation recapture, and debt. Have your CPA run the actual numbers rather than eyeballing the cap.
A further like-kind exchange does not recognize gain, so the deferral continues and so does the Form 3840 obligation. The clawback follows the deferral, not the address. Dollar figures are illustrations of the mechanics, not a projection for your deal. Confirm with your CPA.
The Reason This Page Exists
Everything above is background. The scenario: you did the exchange years ago, you now live in Idaho, and you sell the Idaho property in a taxable sale. Two states speak at once.
| State | What it says |
|---|---|
| California | Part of that gain is California-source deferred gain, taxable here at up to 12.3% plus the 1% Behavioral Health Services Tax on income over $1,000,000. |
| Idaho | You are an Idaho resident and you sold Idaho property. Taxable here at 5.3%. |
Same dollars. Two states. Does anyone give you relief?
Direction matters. Normally the resident state credits you for tax paid to the source state. There is an exception category, reverse credit states, where California credits its nonresidents instead. California’s Schedule S instructions limit that treatment to nonresidents residing in Arizona, Guam, Oregon, or Virginia. Idaho is not on that list. So no relief comes from the California direction. If it exists, it has to come from Idaho. (FTB Schedule S)
What Idaho’s credit rule says. Idaho Code 63-3029 gives a resident a credit for income taxes paid to another state on income derived from sources therein while domiciled in Idaho and also subject to Idaho tax. The credit is capped at the lesser of the tax actually paid to the other state or the proportion of Idaho tax the out-of-state income bears to total income, computed state by state. (Idaho Code 63-3029 | IDAPA 35.01.01.700)
Then comes the sentence that creates the problem. Idaho’s rule provides that income derived from the ownership or disposition of any interest in real or tangible personal property located in the other state is to be considered income derived from sources in the other state, and Idaho determines source using its own nonresident sourcing rules under section 63-3026A. Apply that to your facts. What property did you dispose of? Idaho property. The building is in Idaho. Under Idaho’s own definition, the gain is Idaho-source income, not California-source income.
California’s claim rests on a different theory entirely. California is not saying you sold California property. California is saying the deferred gain originated in California and never lost its California character, no matter what asset it is currently sitting inside. That is a California statutory construct under R&TC 18032 and 24953. Two states, two internally consistent theories, one set of dollars. Idaho’s credit statute is written around a sourcing concept that does not obviously reach California’s clawback theory.
We could not find published Idaho guidance on this exact question
Not a ruling, not a form instruction, not an FAQ. So the honest answer is this: nobody should tell you with confidence whether Idaho will allow the credit. Take this to a CPA who handles multistate work before you sell, not after.
The stakes are real. If Idaho allows the credit, your total state tax is roughly the California number, because California’s rate is higher and the credit absorbs the Idaho tax. If Idaho denies the credit, you pay California on the California-source portion and Idaho on the full Idaho gain, and your combined state bill is materially higher than either state’s rate suggests. On a large gain that spread is worth real money. It is worth paying a CPA to analyze before you sign a purchase agreement.
If you never left California
Cleaner picture. California taxes residents on income from all sources, including the Idaho gain. Idaho taxes you as a nonresident on the Idaho-source gain. California, as your resident state, allows an Other State Tax Credit on Schedule S, and Idaho is listed among the states for which California residents may claim it. You still file the 3840 every year, but the credit mechanism is well established. The irony is worth naming: moving to Idaho lowers your rate on future income and may complicate the credit on the one transaction California has been tracking all along.
Good Rate. Not Zero.
| Rate | Detail |
|---|---|
| Idaho individual and corporate income tax | 5.3% flat. |
| Idaho capital gains | Same 5.3%. No separate capital gains rate. |
| California top individual bracket | 12.3%, plus 1% on income over $1,000,000. |
The 5.3% came from House Bill 40, signed March 6, 2025, cutting the rate from 5.695% retroactive to January 1, 2025, the fourth consecutive year Idaho cut retroactively. The gap versus California is real. But 5.3% is not zero, and that changes the arithmetic for anyone who ran a Nevada comparison in their head. (Tax Foundation | EY Tax News)
Filing
Idaho conforms to the Internal Revenue Code and starts from your federal figures, so a valid federal 1031 is deferred for Idaho too. Idaho Code 63-3026A sources income from the ownership or disposition of any interest in real or tangible personal property located in Idaho to Idaho, and nonresidents with more than $2,500 of Idaho-source income must file. Stay in California, buy in Boise, and you are now an Idaho filer. (Idaho State Tax Commission | Idaho Code 63-3026A)
The 60% capital gains deduction, and the trap inside it
Idaho allows a deduction of up to 60% of capital gain net income from the sale or exchange of qualifying Idaho property, under Idaho Code 63-3022H. Investment real property qualifies. It must be held at least 12 months and sold on or after January 1, 2005. No requirement that it be a farm or an operating business. You claim it on Idaho Form CG. (Idaho State Tax Commission)
- Catch one: the property has to be in Idaho. The Tax Commission is explicit that real or tangible personal property not located in Idaho does not qualify. So the deduction does nothing for the California-source gain California is clawing back. It reduces Idaho tax on Idaho property. It does not reduce California’s bill by a dollar.
- Catch two: your holding period may not carry over. Idaho generally follows IRC section 1223 but carves out an exception: the holding period of property given up in a tax-free exchange is not tacked on if the property given up was nonqualifying property. California property is not qualifying Idaho property, so on a plain reading your Idaho clock starts when you acquire the Idaho property. This is our reading of the regulation applied to this fact pattern, not published guidance on it. Twelve months is a low bar, but if you were planning a quick resale, confirm the reading with your CPA. (IDAPA 35.01.01.171)
Property tax and transfer tax
- Homeowner’s exemption. Exempts 50% of the value of a home and up to one acre, capped at $125,000 in the Tax Commission’s published table for 2021 through 2025. It requires that you own and occupy the home as your primary residence, so your fourplex, strip center, or industrial building gets none of it. If you underwrote off a friend’s Idaho tax bill, check whether that bill had the exemption applied.
- Circuit breaker. A property tax reduction of $250 to $1,500 for owners who are 65 or older, disabled, widowed, or otherwise qualifying, under an income limit. It also requires a primary residence with a current homeowner’s exemption, so it never touches an investment portfolio.
- Effective rate. Idaho’s effective property tax rate on owner-occupied housing runs about 0.50%, with meaningful variation by county. Investment property is assessed without the homeowner’s relief, so build your pro forma accordingly.
- Transfer tax. Idaho does not appear to impose a state real estate transfer tax, a genuine closing-cost difference from California cities that levy documentary transfer taxes. We were not able to locate a primary Idaho Code citation for the prohibition, so treat this as reliable in practice and confirm the legal basis with Idaho counsel if it is material. Recording and title charges still apply.
(Homeowner’s Exemption | Circuit Breaker) Figures are illustrative of the rules, not a quote for any parcel. Confirm current numbers with the county and your CPA.
The Four People Miss
Idaho is not a no-tax state
Investors who mentally filed Idaho next to Nevada and Texas are surprised by a 5.3% rate and an Idaho return. Good rate. Not zero.
Form 3840 outlives your memory of it
Five years later a new CPA who never saw the exchange does not know to file. Then the FTB letter arrives. Keep the exchange file, the closing statement, and the original 3840 where your CPA will find them.
The clocks do not care that you shop remotely
The 45 and 180 day windows still run. Line up Idaho representation, lending, and inspection resources before you close the California sale.
Idaho is not the deal it was
Ada and Canyon counties grew from 726,072 residents in 2020 to 876,760 in 2026, and Meridian became Idaho’s second-largest city. Pricing reflects that.
Keep or sell comes first
Before you get near a Qualified Intermediary, decide whether you should sell at all. Some owners want out of a property. Some want out of active management. Some want a different income profile. A 1031 into a comparable out-of-state building only solves the first one. Exchange a California fourplex you manage yourself for an Idaho fourplex you now manage from 600 miles away and you have added a plane ticket to your problem. Run the keep-or-sell analysis first, with the clawback and the credit question priced in.
Questions Owners Ask on This Route
Yes. The requirement applies to all taxpayers who exchange California real property for out-of-state like-kind property regardless of residence status or commercial domicile, and it runs for the year of the exchange and every year after until the California-source deferred gain is recognized. When the gain is recognized you file a Final Form 3840 with a statement explaining the disposition.
Yes, at Idaho’s flat 5.3% rate, the same rate applied to other income. Idaho does allow a deduction of up to 60% of capital gain net income from the sale or exchange of qualifying Idaho property held at least 12 months.
No. The deduction applies only to qualifying property located in Idaho. The clawback gain came from a California property, and Idaho’s deduction reduces Idaho tax on Idaho property only.
The honest answer is that this is unsettled, and you should not assume it either way. Idaho Code 63-3029 gives residents a credit for taxes paid to another state on income derived from sources therein. But Idaho’s rule sources gain from real property to the state where the property is located, and the property you sold is in Idaho. California’s clawback rests on a different theory. We found no published Idaho guidance resolving the conflict. Get a multistate CPA involved before you sell.
No. California allows nonresidents to claim its Other State Tax Credit only if they reside in Arizona, Guam, Oregon, or Virginia. Idaho residents cannot claim a California credit under that provision. California residents, however, may claim a Schedule S credit for taxes paid to Idaho.
Yes, assuming it qualifies. But a further like-kind exchange does not recognize the gain, so the California deferred gain stays deferred and the Form 3840 obligation continues.
Weighing a California sale against an Idaho buy?
Matt Bingaman works Greater Sacramento commercial real estate, and this is the work he does. A short conversation now is worth more than a correction later. Fifteen minutes, no pitch. Matt is not a tax or legal advisor and coordinates closely with your CPA and Qualified Intermediary.
Sources and References
Federal
California
- FTB: Reporting Like-Kind Exchanges
- FTB: 2025 Form 3840 Instructions
- FTB: Publication 1100
- FTB: 2025 Schedule S Instructions
Idaho
- Idaho Code: Section 63-3029
- IDAPA 35.01.01.700
- Idaho State Tax Commission: Conformity to the IRC
- Idaho Code: Section 63-3026A
- Idaho State Tax Commission: Capital Gains Deduction
- IDAPA 35.01.01.171
- Idaho State Tax Commission: Homeowner’s Exemption
- Idaho State Tax Commission: Property Tax Reduction (Circuit Breaker)