1033 Tax Rules: Triggers, Deferral Election, and Replacement Property

A Section 1033 involuntary conversion is the tax rule that lets you postpone paying tax on the gain when property is taken from you by a casualty, theft, or government condemnation and you receive money or other property in return. The gain is deferred, not forgiven: it rolls into a lower basis on whatever you buy to replace what you lost, so the tax bill catches up when you sell that replacement. To get the deferral, you have to reinvest enough of the proceeds in qualifying replacement property within a two-, three-, or four-year window and elect the treatment on your return.

What Triggers a Section 1033 Conversion

The statute reaches four kinds of events: destruction (fire, storm, flood, earthquake), theft, seizure or requisition by a government, and condemnation or the threat of condemnation under eminent domain.¹ The compensation typically arrives as an insurance payout, a condemnation award, or the proceeds of a sale made under threat of condemnation.

The “threat of condemnation” branch is where most disputes arise. Selling to a government buyer at a negotiated price does not, by itself, qualify. The threat must have been real: the condemning authority had to have both the power and the intent to take the property if you refused. Taxpayers who cannot show that a genuine threat existed before they signed lose the deferral.

When Deferral Is Automatic and When You Have to Elect It

Section 1033 actually operates in two modes. If your property is directly replaced with similar property (an insurer swaps in equivalent equipment instead of cutting a check, for example), no gain is recognized and no election is required. The old basis simply carries over.²

The far more common path is the money path: you collect insurance proceeds or a condemnation award, then go buy replacement property yourself. Here deferral is not automatic. You have to affirmatively elect it on your return, meet the replacement-property standard, and finish the purchase within the statutory window.

How Much Gain Gets Deferred

Your realized gain is the proceeds minus your adjusted basis in the lost property. How much of that gain is deferred depends entirely on how much of the proceeds you reinvest.¹

Say a rental property with a $100,000 adjusted basis is destroyed and you collect $500,000 in insurance. Your realized gain is $400,000. Spend $500,000 or more on qualifying replacement property and the whole $400,000 is deferred. Spend only $450,000 and the $50,000 you kept is taxable now; the other $350,000 rides.

The Basis Carryover

The deferred gain reappears as a reduction to the basis of the replacement property. Cost of replacement minus deferred gain equals your new basis. In the full-deferral example, a $500,000 replacement carries a basis of just $100,000. In the partial-deferral version, the basis is $150,000: $100,000 plus the $50,000 you already paid tax on.¹

For business or rental replacements, depreciation runs off that lower basis, not the price you paid. Smaller depreciation deductions over the holding period partially offset the upfront benefit of the deferral.

What Qualifies as Replacement Property

Two different standards apply, and the trigger for your conversion decides which one you get.

Similar Use for Casualties and Theft

When the loss came from a casualty or theft, the replacement has to be “similar or related in service or use” to what you lost.¹ This is a strict, function-focused test. A manufacturing plant has to be replaced with another manufacturing facility, not a warehouse. A rental apartment building has to be replaced with rental property, not an office you occupy yourself. The IRS applies the test more forgivingly to owner-investors like landlords than to owner-users who run their own operations out of the property, but the through-line in either case is that the replacement must fill the same role.³

Like-Kind for Condemned Real Property

For real property held for business or investment that is condemned or sold under threat of condemnation, the standard loosens to “like-kind,” the same test used in Section 1031 exchanges.⁴ A condemned office building can be replaced with raw investment land, or an industrial parcel with a retail building, as long as both sides are held for business or investment.⁵ The looser test does not extend to casualty or theft losses, and it does not reach inventory or property held primarily for sale to customers.

Buying Stock Instead of Property

You can also satisfy the reinvestment requirement by acquiring at least 80 percent of the stock of a corporation that owns qualifying replacement property. The 80 percent threshold means control: 80 percent of the total combined voting power and 80 percent of each other class of stock.¹ This path is not available for condemned real property claimed under the like-kind standard.

How Long You Have to Replace

The replacement clock does not start on the date the property was lost. It starts at the end of the tax year in which you first realize gain from the conversion, which can add months if the event occurred early in the year.

Two years. The standard window. Gain realized in 2025 must be reinvested by December 31, 2027.¹
Three years. Real property used in a trade or business or held for investment that is condemned gets an extra year.⁶
Four years. A principal residence or its contents destroyed in a federally declared disaster.

Getting More Time

If you cannot close on replacement property before the window shuts, you can request an extension from the IRS, generally limited to one year. You have to show reasonable cause, such as construction that will not finish on schedule. The IRS wants the request in hand before the period expires, though it will consider a late one if you explain the delay. High prices and a thin inventory of comparable properties are, per the IRS, not reasonable cause.⁷

If a Principal Residence Was Destroyed

Homeowners get an unusually generous outcome because Section 121 and Section 1033 stack. Section 121 excludes up to $250,000 of gain on the sale of a principal residence ($500,000 for a married couple filing jointly), and the tax code treats an involuntary conversion as a sale for this purpose. You apply the Section 121 exclusion first, then defer any remaining gain under Section 1033 by buying a replacement home within the applicable window.

The math: a home with a $200,000 basis, $700,000 in insurance proceeds, single filer. Gain is $500,000. Section 121 knocks out $250,000. The remaining $250,000 can be deferred if you spend at least $450,000 on a replacement (the $700,000 in proceeds reduced by the $250,000 exclusion). Basis is reduced only by the amount deferred under 1033, not by the Section 121 exclusion. To claim the exclusion in the first place, you have to have owned and used the home as a principal residence for at least two of the five years before the conversion. Time in the old home also counts toward the ownership and use tests for a future Section 121 claim on the replacement.

Federally Declared Disasters

Section 1033(h) layers two more benefits on top for a principal residence lost in a federally declared disaster. Insurance proceeds for unscheduled personal property (the ordinary household contents covered under a general homeowner’s policy) are excluded from income entirely, with no reinvestment required.⁸ And the replacement window for the residence itself stretches to four years, which matters when a whole community is being rebuilt at once. The IRS also routinely postpones filing and payment deadlines for taxpayers in covered disaster areas, and those postponements can affect Section 1033 replacement dates.⁹

Depreciation Recapture Still Applies

Deferring gain does not automatically defer depreciation recapture. On business or rental property, the portion of gain attributable to prior depreciation can be pulled out as ordinary income under Section 1245 or 1250 rather than taxed at capital-gain rates. The recapture is capped at the gain you actually recognize on the conversion plus the fair market value of any replacement property that isn’t itself depreciable.¹⁰ Fully reinvest into qualifying depreciable property and recapture typically defers along with the rest. Reinvest only partially, or reinvest into something like raw land, and part of what you thought was a capital gain can come back at ordinary rates. Run the numbers before you close.

How to Elect and Report the Deferral

The reporting unfolds across at least two tax years, and the first-year filing carries the election. Get it wrong and the deferral can be lost.

In the Year of Conversion

Report the conversion on that year’s return and attach a statement electing Section 1033 treatment. The statement should describe the converted property, the circumstances of the loss, the gain realized, and your intent to acquire replacement property within the statutory period. Business property flows through Form 4797.¹¹ Casualty and theft events are first reported on Form 4684, and the gain then carries to Form 4797. Gains on personal-use property such as a home (after any Section 121 exclusion) go on Schedule D and Form 8949.³

In the Year You Buy the Replacement

Report the acquisition on that year’s return: cost, date, and description. This finalizes the election and locks in the replacement property’s adjusted basis.

If You Miss the Window

If the replacement period expires without a qualifying purchase, or you spend less than the full proceeds, file an amended return (Form 1040-X for individuals) for the year the gain was originally realized, report the previously deferred gain, and pay the tax plus accrued interest.³

The Statute of Limitations Stays Open Longer

One quirk worth flagging: the IRS has at least three years from the date you notify it that you have replaced the property (or decided not to) to assess any deficiency tied to the conversion gain.¹ That can extend well past the ordinary three-year audit window. Keep the original property’s basis records, the conversion proceeds documentation, and the replacement purchase records indefinitely rather than trusting the usual retention period.

1
Office of the Law Revision Counsel. 26 US Code 1033 – Involuntary Conversions
2
eCFR. 26 CFR 1.1033(a)-2 – Involuntary Conversion Into Similar Property, Into Money or Into Dissimilar Property
3
Internal Revenue Service. Publication 544 (2025), Sales and Other Dispositions of Assets
4
Office of the Law Revision Counsel. 26 US Code 1033 – Involuntary Conversions – Section 1033(g)
5
GovInfo. 26 CFR 1.1033(g)-1 – Condemnation of Real Property Held for Productive Use
6
Office of the Law Revision Counsel. 26 US Code 1033 – Involuntary Conversions – Section 1033(g)(4)
7
Internal Revenue Service. Involuntary Conversion: Get More Time to Replace Property
8
Office of the Law Revision Counsel. 26 US Code 1033 – Involuntary Conversions – Section 1033(h)
9
Internal Revenue Service. IRS Announces Tax Relief for Taxpayers Impacted by Severe Winter Storms in the State of Louisiana
10
Office of the Law Revision Counsel. 26 US Code 1245 – Gain From Dispositions of Certain Depreciable Property
11
Internal Revenue Service. About Form 4797, Sales of Business Property