1031 Exchange Boot: What It Is, How It's Taxed, and How to Avoid It

Boot is any value you take out of a 1031 exchange that does not qualify for tax deferral — cash you keep, debt you shed, or equity you fail to reinvest. Even a small miscalculation can trigger a six-figure tax bill in the same year you thought you had fully deferred.

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What is boot in a 1031 exchange?

Under IRC §1031, a like-kind exchange defers capital gains and depreciation recapture — but only if the investor reinvests all net equity and matches or exceeds the debt on the relinquished property. Any value that leaks out of those two requirements is called boot.

"Boot" is not a statutory term. It is the practitioner shorthand for the portion of an exchange that the IRS taxes immediately in the year of the transaction. Investors who expected to defer all gain are often surprised to learn they owe six figures within 90 days of a closing they assumed was clean.

Key rule: recognized gain ≤ realized gain. The amount you owe tax on cannot exceed your total realized gain on the sale. If your boot is larger than your gain, you only pay tax up to the gain. But this is rarely a planning tool — the IRS's ordering rules mean the most expensive gain layers (recapture, NIIT) hit first.

Two types of boot

Cash boot

Cash boot is the straightforward type: money received at or after closing that is not reinvested into qualifying replacement property. Common sources include:

Proceeds released by the qualified intermediary (QI) before the exchange closes
Replacement property priced lower than the relinquished property net sale value
Prorated rents or security deposits transferred at closing (depending on how contracts are written)
Non-like-kind property included in the sale (personal property such as furniture or equipment is not like-kind to real estate after TCJA 2018)⁴

Mortgage boot (debt relief boot)

This is the type that catches investors off guard. Mortgage boot occurs when the debt on the replacement property is lower than the debt paid off on the relinquished property. The IRS treats the net debt reduction as a cash distribution — taxable boot — even if no cash actually changed hands.

Example: You sell a property with $700,000 of mortgage paid off at closing. You buy a replacement and take on $500,000 of new debt. The $200,000 gap is mortgage boot — taxable in the exchange year — even if every dollar of equity was reinvested into the replacement property.

Mortgage boot is the most common source of surprise tax bills in 1031 exchanges. Investors focus on the equity math — "I reinvested everything" — and overlook the debt-side requirement. To eliminate mortgage boot, the new debt must equal or exceed the old debt. If you cannot find a replacement with enough leverage, you must make up the shortfall with additional cash equity out of pocket.

How boot is taxed

Boot recognition triggers gain recognition. The IRS applies a specific order to that gain:

Depreciation recapture first. Accumulated depreciation is recaptured first at a maximum federal rate of 25% under the unrecaptured §1250 gain rules.¹ If your boot is $200,000 and your accumulated depreciation is $280,000, the entire $200,000 of recognized gain is classified as recapture — taxed at up to 25%, not the lower long-term rate.
Long-term capital gain next. Any recognized gain that exceeds the recapture amount is taxed at long-term capital gains rates — 0%, 15%, or 20% depending on taxable income.² Most investors with seven-figure investment properties are in the 20% bracket.
Net Investment Income Tax (NIIT) on top. The 3.8% NIIT applies to both the recapture and the capital gain layers to the extent your modified AGI exceeds $200,000 (single) or $250,000 (married filing jointly).³
State income tax. Most states tax recognized gain in the year of the exchange. Rates range from 0% (Florida, Texas, Wyoming, Nevada) to 13.3% (California). Some states do not conform to §1031 deferral at all.

Adding the federal layers: recapture is taxed at 25% + 3.8% NIIT = 28.8% combined. Long-term gain above recapture is taxed at 20% + 3.8% = 23.8% combined federal. Both layers are then subject to state tax.

Worked example: $250,000 of mortgage boot

An investor sells a commercial property and buys a replacement that carries less debt than the old property. Everything else looks correct on the surface.

Relinquished property	Amount
Sale price	$2,400,000
Selling costs	($140,000)
Net sale value	$2,260,000
Adjusted tax basis	($750,000)
Realized gain	$1,510,000
Accumulated depreciation	$380,000
Old mortgage paid off at closing	$800,000
Net equity (after debt payoff)	$1,460,000

Replacement property: Purchased for $2,210,000 with $550,000 new mortgage. All equity reinvested ($1,460,000 + $200,000 additional cash = $1,660,000 → no, that math doesn't work).

Let's be precise:

Replacement property price: $2,050,000
New mortgage: $550,000
Cash equity needed: $1,500,000 — investor reinvests full $1,460,000 equity plus $40,000 additional cash
Cash boot: $0 (all equity reinvested)
Mortgage boot: $800,000 − $550,000 = $250,000

Boot tax calculation (top federal brackets)	Amount	Rate	Tax owed
Recognized gain (= boot, capped at realized gain)	$250,000	—	—
Allocated to recapture (§1250, max 25%)	$250,000	25%	$62,500
Remaining as long-term gain	$0	20%	$0
NIIT on all recognized gain	$250,000	3.8%	$9,500
Total federal tax on boot			$72,000

Adding California's 9.3% state rate on the $250,000 raises the total to roughly $95,250. The investor believed the exchange was clean. The $250,000 mortgage shortfall — not a decision, just a debt structure on the replacement — triggered nearly $100,000 in immediate taxes.

Use the calculator to estimate your own boot exposure →

How to avoid boot in a 1031 exchange

Buy equal or greater value. The replacement property purchase price must be at least equal to the net sale value (sale price minus selling costs). Buying even slightly down creates cash boot on the difference — and the math compounds quickly on $1M+ sales.
Match or exceed the old debt. Take on at least as much debt on the replacement as you paid off on the relinquished property. If new debt is lower, fund the gap with additional cash equity from your own reserves. If you do not have the cash, consider whether the exchange still makes sense compared to a taxable sale.
Reinvest all equity through the QI. Do not instruct the qualified intermediary to release cash to you at any point during the exchange. Any funds that touch your hands before the replacement closes are boot by definition.
Exclude personal property from the sale. After TCJA (2018), personal property no longer qualifies for like-kind exchange treatment. If fixtures, equipment, or furnishings are part of the deal, allocate their value carefully in the purchase contract — otherwise their full value may be treated as boot.
Identify replacement before the relinquished sale closes. Investors who know what they are buying before the 45-day identification window opens have the most control over the debt and equity math. Last-minute replacements often force price or leverage compromises that create boot accidentally.

When accepting boot might be the right call

Avoiding boot is almost always the goal. But the decision is not purely mechanical. There are situations where accepting some boot — or abandoning the exchange entirely — produces a better outcome than forcing a clean exchange into a bad replacement property.

No good replacement available

If the only qualifying property would over-concentrate the portfolio in weak real estate, take on excess leverage, or produce poor income relative to the tax deferred, the boot tax may be cheaper than the investment risk locked in for years.

Portfolio rebalancing

Accepting controlled cash boot lets investors redirect proceeds into financial assets, pay off other debt, or fund near-term spending without fully exiting real estate. A partial exchange with deliberate boot is better than none.

State tax timing

An investor relocating from a high-tax state (California, New York) to a no-income-tax state (Florida, Texas) may choose to time the exchange or accept some boot after establishing new residency to reduce the state layer.

Estate planning at later life stages

Heirs receive a stepped-up basis at death, eliminating all deferred gain. For investors with serious health concerns, accepting the boot tax now and simplifying the estate may outweigh continued deferral into a concentrated property position.

None of these judgments are mechanical. A financial advisor can model the after-tax outcome for each scenario — full exchange, partial boot, taxable sale, DST — before the 45-day deadline forces the decision.

Boot and the exchange clock

Boot is almost always a planning problem, not a compliance problem. The investors who pay the most unnecessary boot tax are the ones who miscalculate the debt math under time pressure:

You have 45 days from the relinquished property closing to identify replacement properties in writing. Missing this window collapses the exchange entirely and triggers recognition of all realized gain.
You have 180 days from the closing (or until the tax return due date with extensions, whichever is earlier) to close on the identified replacement.
Mortgage boot most often appears in the final week before the 180-day deadline when the only remaining available property carries less leverage than the original plan assumed — and the investor closes anyway rather than abandon the exchange.

Running the debt replacement math before signing the replacement purchase contract — not after — is the difference between a clean exchange and an unexpected tax bill at April filing.

Read the full 1031 exchange planning checklist →

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Sources

IRS Publication 544, Sales and Other Dispositions of Assets — unrecaptured §1250 gain subject to maximum 25% rate. irs.gov/publications/p544
IRS Topic No. 409, Capital Gains and Losses — long-term capital gains rates 0%/15%/20% based on taxable income. irs.gov/taxtopics/tc409
IRS Topic No. 559, Net Investment Income Tax — 3.8% surtax applies above $200,000/$250,000 MAGI thresholds. irs.gov/taxtopics/tc559
IRS Tax Reform Guidance, Like-Kind Exchanges — TCJA (2017) limited IRC §1031 deferral to real property exchanges effective January 1, 2018. irs.gov/newsroom/like-kind-exchanges-real-estate-tax-tips

Tax values verified as of May 2026 against IRS.gov. Content is for informational purposes only and does not constitute financial, tax, legal, real estate, or investment advice. Section 1031 rules are complex and should be reviewed with qualified tax and legal professionals.