What Is Boot in a 1031 Exchange? Cash Boot, Mortgage Boot, and the Netting Rules That Determine Your Tax Bill

The word "boot" does not appear anywhere in the Internal Revenue Code. You will not find it in IRC §1031, in the Treasury Regulations, or in any IRS publication. Yet it is the single most important concept in determining whether a 1031 exchange is fully tax-deferred, partially tax-deferred, or a tax bill waiting to happen.

This article explains what boot is, where the concept comes from, how the two most common forms — cash boot and mortgage boot — interact under the netting rules, and why the ordering rules for gain recognition mean that even a small amount of boot can produce a disproportionately large tax bill.

The Statutory Origin of Boot

IRC §1031(a) provides the general rule: no gain or loss is recognized when property held for productive use in a trade or business or for investment is exchanged solely for property of a like kind. The operative word is "solely."

IRC §1031(b) addresses what happens when the exchange is not solely for like-kind property:

"If an exchange would be within the provisions of subsection (a) ... if it were not for the fact that the property received in exchange consists not only of property permitted by such provisions to be received without the recognition of gain, but also of other property or money, then the gain, if any, to the recipient shall be recognized, but in an amount not in excess of the sum of such money and the fair market value of such other property."

That phrase — "other property or money" — is what practitioners call "boot." The statute does not use the word. Tax professionals adopted it from old English legal usage, where "to boot" meant "in addition to" or "thrown in to equalize a bargain." The story, likely apocryphal but widely repeated in exchange circles, is that during hearings before the Senate Finance Committee while Congress was considering amendments to Section 1031, a Senator struggling to understand partial non-recognition finally said something to the effect of: "Ohhhhh — you mean money or other property received, to boot!" Whether or not the exchange happened exactly that way, the term stuck.

The principle is straightforward: everything you receive that is not like-kind real property is boot. And boot is taxable — up to the amount of your realized gain.

The Three Categories of Boot

Boot takes three forms. Understanding the distinction matters because the netting rules treat each category differently.

Cash Boot

Cash boot is the most intuitive form. It occurs when the exchanger receives money from the transaction that is not reinvested in replacement property.

Common sources of cash boot:

Not reinvesting all net proceeds. You sell for $800,000. After closing costs and a $300,000 mortgage payoff, the QI holds $475,000. You purchase an $850,000 replacement property with a $400,000 mortgage — the QI wires $450,000 to closing. The remaining $25,000 held by the QI is returned to you. That $25,000 is cash boot.
Taking cash at the relinquished property closing. The closing statement includes a wire to the seller for a commission rebate, a repair credit, or an agreed-upon disbursement. Any amount wired to the exchanger — rather than to the Qualified Intermediary — is boot.
Non-qualified closing costs paid from exchange funds. Certain expenses — property taxes owed before closing, HOA dues, utility prorations, tenant security deposit transfers, and home warranties — are not considered exchange expenses under the regulations. When exchange funds are used to pay them, the IRS may recharacterize those payments as constructive receipt of cash boot.
Rent prorations. If the closing statement assigns a rent proration credit to the seller and the QI does not receive those funds, the proration may be treated as boot.

The critical rule: exchange funds must flow to the QI. Any amount that reaches the exchanger's hands — directly or constructively — is cash boot.

Mortgage Boot (Debt Relief Boot)

Mortgage boot is less intuitive but equally important. It occurs when the debt on the replacement property is less than the debt on the relinquished property.

The logic is economic: if you owed $400,000 on the old property and the buyer paid off that mortgage at closing, you received $400,000 in value — your debt was extinguished. If you then finance only $300,000 on the replacement property, you have received $100,000 in net debt relief. The IRS treats that $100,000 as boot.

Treas. Reg. §1.1031(j)-1 governs the treatment of liabilities in exchanges. The regulation makes clear that the assumption of the exchanger's liabilities — or the acquisition of property subject to the exchanger's liabilities — is treated as the receipt of "other property or money" under §1031(b).

Common sources of mortgage boot:

Trading down in value. Selling a $900,000 property with a $400,000 mortgage and purchasing a $700,000 replacement with a $200,000 mortgage. The QI holds $475,000 after closing costs and debt payoff. The replacement closing requires $500,000 in non-mortgage funds ($700,000 − $200,000), and the QI provides $475,000, so the investor brings only $25,000 in outside cash. But debt decreased by $200,000 ($400,000 → $200,000). The $25,000 in outside cash offsets $25,000 of that debt relief, leaving $175,000 in taxable mortgage boot.
Paying off lines of credit. If the relinquished property closing pays off a home equity line of credit secured by the property, that payoff is treated as debt relief. If the replacement property does not carry equivalent debt, the payoff creates mortgage boot.
Cash purchases. An investor who sells a leveraged property and purchases the replacement property for all cash has reduced their debt by the full amount of the relinquished property mortgage — creating mortgage boot equal to the entire debt payoff.

Property Boot (Non-Like-Kind Property)

The third category is less common but occasionally significant. Property boot occurs when the exchanger receives non-like-kind property as part of the transaction — personal property (furniture, equipment, vehicles), promissory notes, or financial instruments. The fair market value of the non-like-kind property received is boot.

Since the 2017 Tax Cuts and Jobs Act eliminated 1031 exchanges for personal property, this category arises most often when a transaction includes both real property and personal property that cannot be separated — furnished vacation rentals, restaurants with FF&E, or agricultural properties with equipment.

The Netting Rules: Where Most Investors Get It Wrong

Here is the concept that produces more tax surprises than any other in 1031 exchange practice: the netting rules are asymmetric.

When an exchange involves both cash and debt, the IRS does not simply net everything together. The rules allow certain offsets but prohibit others:

Boot Paid	Can Offset Cash Boot Received?	Can Offset Mortgage Boot Received?
Cash paid at replacement closing	Yes	Yes
New mortgage on replacement property	No	Yes

The first row is straightforward. If you bring additional cash to the replacement property closing, that cash offsets both cash boot and mortgage boot dollar for dollar.

The second row is the trap. Increasing your mortgage on the replacement property offsets mortgage boot — but it does not offset cash boot. If you took $50,000 in cash out of the exchange and then borrowed $50,000 more on the replacement property, you might assume those wash. They do not. The $50,000 cash boot is still taxable.

Why the Asymmetry Exists

The logic is that cash received represents actual economic benefit — money in the exchanger's pocket. Borrowing more money on the replacement property does not undo that benefit. The exchanger received cash and incurred new debt — two separate economic events. The IRS will not allow one to cancel the other.

Conversely, bringing additional cash to the replacement closing does offset mortgage boot because it replaces the economic value that would otherwise have been provided by debt. The exchanger is substituting equity for leverage — a genuine economic investment that offsets the debt reduction.

A Practical Example

Consider this transaction:

Relinquished property: Sold for $800,000 with a $300,000 mortgage payoff. Net proceeds to QI: $475,000 (after closing costs).
Replacement property: Purchased for $850,000 with a $200,000 new mortgage. Funds from QI: $475,000. Cash from exchanger's savings: $175,000.

The investor traded up in value and reinvested every dollar held by the QI. No cash boot.

Mortgage boot analysis: Debt decreased by $100,000 ($300,000 → $200,000). But the exchanger contributed $175,000 in outside cash to the replacement closing. Under the netting rules, outside cash offsets mortgage boot dollar for dollar. Since $175,000 exceeds the $100,000 debt reduction, the mortgage boot is fully offset. No mortgage boot.

This is not a coincidence — it is arithmetic. When you trade up in value and reinvest all exchange proceeds, the outside cash you must bring to close will always equal or exceed any debt reduction. The cash you contribute is funding both the higher purchase price and the debt shortfall. The netting rules give you credit for both.

Total boot: $0. Fully deferred.

Now change the facts. Same relinquished property ($800,000 sale, $300,000 mortgage, $475,000 to QI). But this time the investor trades down — purchasing a $650,000 replacement with a $150,000 mortgage:

Replacement closing requires $500,000 in non-mortgage funds ($650,000 − $150,000)
QI provides $475,000. Investor brings $25,000 in outside cash.
Cash boot: The QI has no leftover funds — all $475,000 went to closing. $0.
Mortgage boot: Debt decreased by $150,000 ($300,000 → $150,000). Outside cash is $25,000. Net mortgage boot: $150,000 − $25,000 = $125,000 taxable.

The investor traded down by $150,000 in value. That is why mortgage boot survived netting — the outside cash was not large enough to cover the debt reduction.

Now add one more wrinkle. Same trade-down, but the exchanger also took $30,000 in cash at the relinquished property closing (a seller disbursement wired to a personal account). Can the investor eliminate that cash boot by increasing the replacement mortgage to $180,000?

Mortgage boot: Debt decreased by $120,000 ($300,000 → $180,000). Partially offset by outside cash. Still produces some mortgage boot.

Cash boot: $30,000 received at closing. Can the extra debt offset it? No. Debt does not offset cash boot. Cash boot: $30,000 taxable — regardless of how much the investor borrows on the replacement property.

This is the asymmetry that matters: cash in offsets mortgage boot, but debt does not offset cash boot.

The Ordering Rules: Why Small Boot Creates Large Tax Bills

The netting rules determine how much boot is taxable. The ordering rules determine what kind of tax applies to that boot — and this is where small amounts of boot produce disproportionate pain.

Under Treas. Reg. §1.1031(j)-1 and the general gain recognition rules, recognized gain from boot is allocated in the following order:

Depreciation recapture (§1250 unrecaptured gain) — taxed at a maximum federal rate of 25%
Capital gain — taxed at the applicable long-term capital gains rate (typically 15% or 20%)

The recapture comes first. Always.

Why This Matters

Suppose an investor has $200,000 in total gain, of which $80,000 is depreciation recapture and $120,000 is capital gain. The exchange is almost fully deferred, but the investor received $30,000 in boot.

The $30,000 in recognized gain is allocated first to depreciation recapture. The entire $30,000 is taxed at the 25% recapture rate — none of it receives the lower capital gains rate.

Federal tax on $30,000 boot: $30,000 × 25% = $7,500
Plus 3.8% NIIT: $30,000 × 3.8% = $1,140
Total federal tax on $30,000 of boot: $8,640

That is an effective rate of 28.8% — on what the investor may have assumed would be taxed at 15% or 20%.

If the investor had $30,000 in capital gain and no recapture, the tax would be $5,640. The ordering rules cost the investor an additional $3,000 — on a $30,000 mistake.

For investors who have used cost segregation studies or bonus depreciation, the recapture exposure is even larger. Section 1245 recapture — which applies to personal property components accelerated under cost segregation — is taxed at ordinary income rates, which can reach 37%. Boot allocated to §1245 recapture does not get the 25% ceiling.

Washington State Considerations

For Washington investors, boot recognition creates an additional layer of analysis.

Washington's capital gains excise tax (Chapter 82.87 RCW) exempts direct sales of real property. Gains deferred through a 1031 exchange are not included in taxable income because they are excluded from federal Adjusted Gross Income. But boot is not deferred — it is recognized as gain at the federal level and included in AGI.

The interaction with Washington's 9.9% income tax (ESSB 6346) depends on the character of the boot:

Long-term capital gain boot from direct real property transfers is generally excluded from Washington's taxable income under the Section 302 subtract-and-add-back mechanism, because direct real property gains are exempt from the capital gains excise tax and therefore are not added back to the income tax base.
Ordinary income boot — specifically depreciation recapture characterized as ordinary income under §1245 — is not excluded by Section 302. This portion of boot may be subject to the 9.9% Washington income tax if the investor's total Washington taxable income exceeds the applicable threshold.

The practical consequence: an investor who takes boot and has significant §1245 recapture exposure (from cost segregation) may face a combined marginal rate exceeding 37% + 3.8% + 9.9% = 50.7% on that portion of the boot. Planning around boot is not optional for Washington investors with high-value exchanges.

The "Trade Equal or Up" Rule

The simplest way to avoid boot entirely is to follow three guidelines:

Purchase replacement property with a fair market value equal to or greater than the relinquished property's sale price.
Reinvest all net equity (exchange proceeds) into the replacement property. No cash comes back to you.
Replace all debt. The mortgage on the replacement property must be equal to or greater than the mortgage on the relinquished property — unless you bring additional cash to cover the shortfall.

If any one of these conditions is not met, boot results.

Here is the insight that most boot discussions miss: when you trade equal or up in value and reinvest all exchange proceeds, any debt reduction is automatically offset by the outside cash you bring to close. The arithmetic guarantees it. The outside cash you contribute funds both the higher purchase price and the debt shortfall — and the netting rules give you credit for both.

Mortgage boot survives netting only when the investor trades down in value. In a trade-down, the outside cash contribution is smaller than the debt reduction — because the investor is not making up a purchase price gap, so there is less cash flowing in to offset the debt flowing out.

Consider:

Sold: $700,000 property, $400,000 mortgage, $275,000 net equity to QI
Bought: $550,000 property, $200,000 mortgage, $275,000 from QI, $75,000 cash from savings

All exchange proceeds reinvested — no cash boot. But debt decreased by $200,000 ($400,000 → $200,000). Outside cash is only $75,000. Net mortgage boot: $200,000 − $75,000 = $125,000 taxable.

The investor chose a less expensive replacement property. That decision — not the financing decision — is what created the boot.

Common Boot Mistakes — and How a Closing Statement Review Prevents Them

The most dangerous boot is the boot you did not intend to receive. These are the patterns we see most frequently:

1. Seller disbursements at the relinquished closing. The closing statement includes a wire to the seller for "miscellaneous" — a contractor payment, a property tax estimate, a commission rebate. Every dollar that goes to the exchanger instead of the QI is cash boot.

2. Non-qualified expenses paid from exchange funds. Property taxes accrued before closing, HOA dues, transfer taxes in certain states, tenant security deposits, and home warranties are not exchange expenses. When the closing agent pays them from the sale proceeds before wiring the balance to the QI, those payments may be treated as boot.

3. Failing to account for debt reduction. The investor focuses on reinvesting all cash but overlooks that the new mortgage is $200,000 less than the old one. Nobody raises the issue until the CPA prepares Form 8824.

4. Personal property included in the purchase price. A furnished vacation rental is sold for $900,000. The purchase agreement allocates $850,000 to real property and $50,000 to furniture and appliances. The $50,000 is property boot — non-like-kind assets received in the exchange.

5. Loan payoffs that include non-real-property debt. The relinquished property closing pays off a home equity line of credit that was used for personal expenses, not property improvements. The payoff creates mortgage boot — and the replacement property may not carry equivalent debt to offset it.

Every one of these mistakes is preventable with a closing statement review before the deed records. This is where the structure of the QI relationship matters. A QI who simply holds funds and executes paperwork will process the closing statement as received. A QI who reviews the closing statement before closing will flag line items that create boot — and work with the closing agent to restructure them before the transaction is final.

At Olympic Exchange Accommodators, every closing statement is reviewed before funding. Line items that would create unintended boot or violate the constructive receipt safe harbor are identified and corrected before the deed records — not after. The difference between a $0 tax bill and a $30,000 tax bill is often a single line item on a closing statement that nobody reviewed.

Partial Exchanges: When Boot Is Intentional

Not all boot is accidental. Some investors intentionally structure a partial exchange — deferring most of the gain while taking some cash or reducing their debt.

A partial exchange is still a valid 1031 exchange. The portion of the gain allocable to the like-kind property received is deferred. The portion allocable to boot is recognized and taxed in the year of the exchange.

The decision to take boot should be deliberate, modeled in advance, and coordinated with the investor's CPA. Key considerations:

What is the character of the recognized gain? If the investor has significant depreciation recapture, even a small amount of boot may be taxed at 25% or higher — not at capital gains rates.
Does the boot push the investor above a tax threshold? For Washington investors, boot recognized as ordinary income could contribute to exceeding the income tax threshold.
Is installment sale treatment available? Under IRC §453, if the exchange fails entirely, the taxpayer may qualify to spread the gain over the installment period. But a partial exchange — where the investor deliberately takes boot — generally does not qualify for installment treatment on the boot received, because the sale proceeds were available in the year of the transaction.
Would a DST fill the gap? If the investor cannot find replacement property for the full exchange amount, a Delaware Statutory Trust interest can absorb the remaining exchange funds and prevent boot. DST investments carry their own risks and limitations, but they eliminate the boot problem.

The Bottom Line

Boot is not a penalty. It is not an error. It is simply the tax consequence of receiving value in a 1031 exchange that is not like-kind real property. The Code permits partial exchanges, and many investors choose them deliberately.

The danger is unintentional boot — the closing statement line item nobody caught, the debt reduction nobody modeled, the non-qualified expense nobody flagged. These are the mistakes that produce unexpected tax bills months after the exchange closes, when the only remaining option is to pay.

The netting rules are asymmetric: cash offsets mortgage boot, but debt does not offset cash boot. The ordering rules are punitive: boot is taxed as depreciation recapture before capital gain, producing higher effective rates on small amounts. And for Washington investors, the interaction with the state's income tax creates additional exposure that did not exist three years ago.

Understanding boot is not optional. It is the difference between a fully tax-deferred exchange and one that costs tens of thousands of dollars more than it should.

At Olympic Exchange Accommodators, we are an attorney-led Qualified Intermediary serving investors throughout Tacoma, Pierce County, the Puget Sound region, and Washington State. Every exchange we facilitate includes a closing statement review before funding — because the line items that create boot are the line items that should be caught before the deed records, not after. If you are planning a tax-deferred 1031 exchange and want to understand how boot affects your specific transaction, contact us for a consultation.

Jeff Helsdon, CES® Certified Exchange Specialist since 2003

Disclaimer: This article is for informational purposes only and does not constitute legal, tax, or financial advice. Every exchange has unique facts and circumstances. Consult your own attorney, CPA, and financial advisor before making decisions about your 1031 exchange.

What Is Boot in a 1031 Exchange? Cash Boot, Mortgage Boot, and the Netting Rules That Determine Your Tax Bill