Partial 1031 Exchange: How Taxable Boot Works

What makes an exchange partial

An exchange becomes partial whenever you receive cash, trade down in value, or reduce your mortgage balance — any amount not reinvested is "boot." Boot can be intentional (you want some cash out) or accidental (a price mismatch in the closing).

How boot is taxed

Boot is taxable up to your realized gain, even in an otherwise valid exchange. The IRS applies boot to the worst tax treatment first: depreciation recapture (up to 25%) is recognized before capital gains. If you have $80,000 in accumulated depreciation and take $50,000 in boot, the full $50,000 is taxed as recapture at up to 25% — not as the more favorable capital gains rate.

Calculating a partial exchange

Realized gain = net sale price − adjusted basis. Amount deferred = the lesser of (a) equity reinvested in the replacement or (b) the full realized gain. Boot = realized gain − amount deferred. Use the 1031 calculator to model the deferred and taxable portions before structuring the deal.

Cash boot vs. mortgage boot

Boot comes in two forms. Cash boot is money or non-like-kind property you actually receive. Mortgage boot (debt-relief boot) arises when the debt on your replacement property is less than the debt paid off on the relinquished property — the IRS treats that reduction in liabilities as if you received cash. The netting rules are asymmetric and easy to get wrong: you can offset net debt relief by bringing new cash into the purchase, and you can offset debt relief with a larger new mortgage. But you cannot wipe out cash you receive by taking on more mortgage — cash actually received in hand is always boot. Only net debt relief (old debt minus new debt, if positive) counts, and only after being offset by any new cash you contribute.

A full worked example

You sell a rental for a net $500,000. Original cost was $300,000, you have taken $100,000 of depreciation, so your adjusted basis is $200,000 and realized gain is $300,000. You pay off the old $200,000 mortgage, leaving $300,000 of equity with your qualified intermediary. You buy a replacement for $450,000 using a new $250,000 mortgage plus $200,000 of the exchanged equity — and pocket the remaining $50,000 in cash. Because your new debt ($250,000) exceeds the old debt ($200,000), there is no mortgage boot. The only boot is the $50,000 cash. Recognized gain = the lesser of boot ($50,000) or realized gain ($300,000) = $50,000. Since you have $100,000 of unrecaptured Section 1250 depreciation, that $50,000 is taxed first as unrecaptured 1250 gain at up to 25%. Deferred gain = $300,000 − $50,000 = $250,000. Your basis in the replacement is $450,000 − $250,000 deferred gain = $200,000.

Trading down creates boot even without cash

You do not have to walk away with a check to trigger boot. If the replacement property is worth less than the one you sold, or you reinvest less equity, the shortfall is boot even if the leftover money technically sits with the intermediary and is returned to you afterward. The two rules of thumb to fully defer: buy equal or greater in value, and reinvest all of your equity, replacing at least as much debt as you shed (or making up the difference with new cash). Miss either target and the gap becomes taxable boot.

How exchange costs affect boot

Legitimate exchange expenses — qualified intermediary fees, sales commissions, title and escrow charges, transfer taxes, and related closing costs — can be paid from exchange funds and reduce the amount of boot without triggering tax. But non-exchange expenses paid out of the proceeds — loan-origination or financing costs on the new mortgage, prepaid property taxes, prorated rents, and insurance reserves — are generally treated as boot received. Have your intermediary and closer separate these line items so financing costs are paid with outside funds, not exchange proceeds.

Reporting boot on Form 8824

A partial exchange is reported on Form 8824, which walks you through realized gain, the value of boot received, and recognized gain. The recognized gain then flows to the appropriate schedule: the unrecaptured Section 1250 portion and any Section 1245 recapture to Form 4797, and any remaining capital-gain portion to Schedule D. The deferred gain is carried in your reduced (substituted) basis in the replacement property, where it waits until a future taxable sale. Keep the closing statements from both properties — you will need the exact debt and cash figures to complete Form 8824 correctly.

When taking boot on purpose makes sense

Deliberate boot is a legitimate planning tool when you want some liquidity out of a highly appreciated property but still wish to defer most of the gain. It can also be paired with suspended passive losses that free up on a partial disposition, or with a low-income year, so the recognized gain is absorbed at a modest effective rate. Just size it with eyes open: because boot hits depreciation recapture first, small amounts of cash can be taxed at the full 25% recapture rate rather than the lower long-term capital-gains rate.

Avoiding accidental boot at closing

Most unplanned boot is a closing-table mistake, not a strategy. Guard against it: never take constructive receipt of the proceeds — all funds must flow through the qualified intermediary, and touching them even briefly can taint the whole exchange. Watch the settlement statement for items that quietly create boot: security deposits transferred to the buyer, prorated rents credited to the buyer, seller credits, and prepaid property taxes. Pay financing costs on the new loan with outside funds, and bring cash to the replacement closing to cover any shortfall rather than letting exchange equity go unused. A short pre-closing review with your intermediary catches nearly all of these.

Boot and the 3.8% net investment income tax

The gain you recognize on boot is not just subject to income tax — for higher earners it can also draw the 3.8% net investment income tax (NIIT). Rental gains are generally investment income, so recognized boot above the modified AGI thresholds ($200,000 single / $250,000 married filing jointly) can carry an extra 3.8% on top of the recapture or capital-gains rate. This is one more reason to keep intentional boot small and, where possible, time it into a year when your income sits below the NIIT threshold.

State tax and withholding on boot

Do not overlook the state layer. The recognized gain from boot is taxable in most states at ordinary state rates, and several states impose real estate withholding at closing on the seller's proceeds — including on exchange transactions — that you reclaim only when you file. A handful of states also apply a clawback, taxing the deferred gain you originally sourced to that state when you eventually sell an out-of-state replacement. Factor both the state income tax on the boot and any mandatory withholding into your net-cash expectation, so the check you walk away with is not smaller than planned.

Boot in reverse and improvement exchanges

The boot rules apply just as forcefully in the more complex exchange structures. In a reverse exchange (you buy the replacement before selling the old property) and a construction or improvement exchange (you build value into the replacement during the exchange period), any value you fail to reinvest by the deadlines becomes boot. A common trap in improvement exchanges: improvements not completed and paid for within the 180-day window do not count toward the replacement value you receive, so an unfinished project can leave you short of the target and holding taxable boot. Coordinate the construction timeline with the exchange deadlines from the outset.

Watch the depreciation restart on the replacement

Recognizing boot does not just create a current tax bill — it also affects how you depreciate going forward. Under Reg. 1.168(i)-6, the carryover portion of your basis continues on the relinquished property's old schedule, while any excess basis from new cash or new debt starts a fresh 27.5- or 39-year life. Boot you recognize is layered into this calculation, and the gain you pay tax on now increases the portion of basis you can depreciate later. Have your preparer set up the two depreciation schedules correctly in the first year after the exchange; fixing a mis-set schedule years later means a Form 3115 accounting-method change.

Frequently asked questions

Is boot always taxed as ordinary income?

No — boot is first allocated to depreciation recapture (unrecaptured Section 1250 gain, up to 25%; Section 1245 recapture at ordinary rates), then to capital gains (0–20%). The order matters.

Can I intentionally take some boot?

Yes. You pay tax on the boot portion and defer the rest. It's a legitimate choice when you want partial liquidity.

Can I offset cash I receive by taking a bigger new mortgage?

No. Cash actually received is always boot. New debt only offsets debt relief (mortgage boot), never cash you take in hand.

Is mortgage boot taxable if I add cash to the deal?

Net debt relief — old debt minus new debt, when positive — is boot, but you can offset it by bringing new cash into the purchase. Only the net reduction after that offset is taxed.

Where do I report a partial 1031 exchange?

On Form 8824. Recognized gain flows to Form 4797 for the recapture portion and Schedule D for any capital-gain portion; the deferred gain stays in your reduced basis.

Does receiving boot invalidate the whole exchange?

No. As long as the exchange otherwise meets the 1031 requirements, only the boot is taxed — the rest of the gain still defers. Boot narrows the deferral; it does not cancel it.

Is boot subject to the 3.8% net investment income tax?

It can be. Recognized gain from boot is generally investment income, so for taxpayers above the modified AGI thresholds ($200,000 single / $250,000 married), an additional 3.8% NIIT may apply on top of the income tax.

Sources

Educational information and estimates only. Not tax advice. Tax rules change and vary by situation; consult a qualified tax professional before acting.

Partial 1031 Exchange and Taxable Boot