The short answer: boot is any value you receive in a 1031 exchange that is not like-kind real estate, most often leftover cash or a reduction in mortgage debt. Boot does not disqualify your exchange, but it is taxable in the year of sale, up to your realized gain. With disciplined planning before closing, most boot is entirely avoidable.
Across the hundreds of exchanges we've guided (more than $1.1 billion in exchange value advised), boot is, without question, the most common reason an investor who expected a fully tax-deferred sale ends up writing a check to the IRS anyway. It rarely happens because someone broke a big rule. It happens in the last ten days of a transaction, in the small print of a closing statement, when nobody is doing the arithmetic. This guide explains what boot is, how it's taxed, where seasoned investors still get caught, and how the 1031 exchange structures we work with every day, including Delaware Statutory Trusts, are used to eliminate it.
What counts as boot in a 1031 exchange?
The word "boot" appears nowhere in Section 1031 of the tax code. It's old trading slang for what gets thrown in "to boot" to even up a swap. In an exchange, it covers three things:
- Cash boot: equity you don't reinvest. Sell for $1,000,000, buy replacement property for $900,000, and the $100,000 difference is taxable, no matter how cleanly the rest of the exchange runs.
- Mortgage boot (debt relief): created when the debt on your replacement property is smaller than the debt retired on the property you sold. Pay off a $400,000 loan and take on only $300,000, and the IRS treats the $100,000 of debt you walked away from as value received.
- Non-qualifying property boot: exchange proceeds applied to anything that isn't like-kind real property, such as furniture and equipment bundled into a sale, or certain non-qualifying costs paid out of exchange funds at the closing table.
The critical nuance (and the one that calms most first-time exchangers down) is that boot does not invalidate the exchange. It converts a fully tax-deferred transaction into a partially tax-deferred one. The boot slice is taxed now; everything else stays deferred.
Cash boot vs. mortgage boot: a worked example
Numbers make this concrete. Say you sell a rental property for $1.2 million carrying a $400,000 mortgage, netting roughly $800,000 in equity after the loan is retired. You then purchase a replacement property for $1.05 million using a $350,000 loan and $700,000 of your equity.
| What happened | Boot created |
|---|---|
| $100,000 of equity never reinvested | $100,000 cash boot |
| New loan is $50,000 smaller than the debt retired | $50,000 mortgage boot |
| Newly taxable this year | Up to $150,000 |
At blended federal capital gains, depreciation recapture, NIIT, and state rates, that's plausibly a $40,000–$55,000 tax bill (illustrative only) from a transaction the investor believed deferred everything. We have sat across the table from that exact conversation more times than we'd like, and it almost always traces back to decisions made in the final two weeks before closing.
How boot is taxed: capital gains, recapture, and state tax
Boot is taxable up to the amount of your realized gain, and the character of that tax matters. Depreciation recapture, taxed federally at up to 25%, is generally recognized first, which surprises long-hold owners whose properties are heavily depreciated. Layer on federal capital gains, the 3.8% net investment income tax where it applies, and state tax (California and New York owners feel this most), and small boot amounts produce outsized bills. Your CPA determines the final character and amount; our role is making sure there's nothing left for them to characterize. If you want a quick estimate of your total exposure before we talk, our Capital Gains Calculator models the combined federal, recapture, and state picture in about a minute.
How to avoid boot: the three rules
Every clean exchange we have ever closed satisfies the same three conditions:
- Trade equal or up in value. The replacement property (or properties) must equal or exceed the sale price of what you relinquished.
- Reinvest every dollar of equity. All net proceeds held by your Qualified Intermediary go into the replacement. None of it touches your account, even briefly.
- Replace the debt. New debt must equal or exceed the debt retired, or the shortfall must be covered with fresh cash. Note the asymmetry: cash can offset reduced debt, but extra debt cannot offset cash you pocket. That one-way rule catches even experienced investors.
Simple to state, hard to execute precisely. Replacement properties rarely price to the exact dollar, and loan sizing rarely mirrors the old mortgage. Precision is a process problem, which is why our four-step exchange process runs these three numbers at identification, at loan commitment, and again at the closing statement.
Where experienced investors still get caught
The textbook rules above are the easy part. In practice, the boot we see most often is accidental, small, and created at the closing table:
- Closing-statement prorations and credits. Rent prorations, security deposit transfers, and repair credits paid out of exchange proceeds can each generate slivers of taxable boot. A few hundred dollars is a rounding error; a $15,000 repair credit is not.
- Earnest money paid from the wrong pocket. Deposits wired personally and later "reimbursed" from exchange funds create a paper trail your CPA will not enjoy unwinding.
- Last-minute loan resizing. Lenders trim proceeds at commitment more often than anyone likes. If the loan shrinks and nobody re-runs the debt-replacement math, mortgage boot appears silently.
- Leftover identification gaps. The 45-day identification list gets built around one primary target; when it closes $80,000 under the required value, there's nothing identified to absorb the remainder.
None of these are exotic. They are the ordinary friction of real transactions, which is exactly why boot prevention is a discipline, not a checklist.
Using a DST to absorb leftover equity
This is where DST investments earn their place in exchange planning. A Delaware Statutory Trust interest qualifies as like-kind replacement property, and because interests are fractional, they can be purchased in nearly exact dollar amounts: $83,412 if that's what your closing statement says is left. If your primary replacement property leaves equity on the table, a DST placed on your 45-day identification list absorbs the remainder and keeps the exchange fully deferred.
Two further points from years of structuring these. First, many DSTs carry non-recourse financing at the trust level (typically around 40–60% loan-to-value depending on the offering), which lets an investor satisfy the debt-replacement rule without personally qualifying for a new loan. Second, we routinely put a DST on the identification list as a backup even when the client fully intends to close on a traditional property: if the primary deal falls through on day 130, the exchange survives. You can see representative offerings on our current property list. DSTs are offered to accredited investors through private placement and carry their own risks, fees, illiquidity, and hold periods. They fit some situations well and others not at all, and we'll tell you which is which.
When boot is a choice: the partial 1031 exchange
Not all boot is a mistake. Some owners deliberately pull a slice of equity out at sale (to retire personal debt, fund a child's home purchase, or simply hold cash) and knowingly pay tax on that slice while deferring the rest. Done intentionally, this is a partial 1031 exchange, and it's a perfectly sound strategy. The distinction we draw with clients is simple: boot should be a decision you make in April of the planning year, not a discovery your CPA makes the following April. For owners weighing a larger step, such as exiting active ownership entirely, a partial exchange sometimes pairs with a longer-term move into a 721 exchange (UPREIT), but that's a strategy conversation, not a closing-week one.
Frequently asked questions about 1031 exchange boot
Does boot disqualify my 1031 exchange?
No. Boot makes the exchange partially taxable, not invalid. Only the boot portion is taxed; the remaining gain stays deferred, provided all other exchange rules are met.
How is boot taxed in a 1031 exchange?
Boot is taxable up to your realized gain, generally as depreciation recapture first (up to 25% federally), then capital gains, plus net investment income tax and state tax where applicable. Your CPA determines the exact character and amount.
Can I offset mortgage boot with cash?
Yes. Adding your own cash to the replacement purchase offsets a reduction in debt. The reverse does not work: taking on extra debt never offsets cash you receive at closing.
What if my replacement property costs less than my sale price?
The shortfall becomes taxable boot unless the remaining equity goes into additional like-kind property, the gap a fractional DST interest is most often used to fill.
Is a partial 1031 exchange allowed?
Yes. You may intentionally take some proceeds as taxable boot and defer tax on the rest. The key is deciding the amount in advance with your advisor and CPA.