Not every 1031 exchange defers 100% of the capital gain. A partial 1031 exchange happens when an investor doesn’t reinvest the full amount of sale proceeds and equity into replacement property — and the portion left out, called “boot,” becomes taxable even though the rest of the exchange still qualifies for deferral.
This page is general and educational. It is not legal or tax advice. Always consult a qualified CPA and 1031-experienced attorney before executing any exchange.
What Is Boot in a 1031 Exchange?
“Boot” is any value received in an exchange that isn’t like-kind replacement real estate — most commonly cash, but also debt relief and non-like-kind property. Boot is taxable to the extent of realized gain, even when the rest of the transaction otherwise qualifies for 1031 deferral. A full exchange isn’t an all-or-nothing proposition: you can defer tax on the reinvested portion while still owing tax on the boot portion.
The Two Main Sources of Boot
Cash boot. This happens when the replacement property costs less than the relinquished property’s net sale price, or when an investor deliberately takes some proceeds out of the exchange rather than reinvesting them fully. The difference is taxable cash boot.
Mortgage (debt) boot. This is the source of boot that catches the most investors off guard. To fully defer gain, the replacement property’s purchase must generally be financed with debt equal to or greater than the debt that was paid off on the relinquished property — or the investor must make up the difference with additional cash. If an investor pays off a $2M mortgage on the relinquished property but only takes on $1.5M of new debt on the replacement property (without contributing additional cash to make up the gap), the $500,000 debt reduction is treated as boot and becomes taxable, even though no cash actually landed in the investor’s pocket.
How to Avoid Unwanted Boot
Match or exceed both value and debt. To fully defer gain, the replacement property generally needs to be equal to or greater in both purchase price and debt level compared to the relinquished property.
Add cash to offset debt reduction. If the replacement property carries less debt than the relinquished property did, contributing additional cash into the purchase can offset the debt-boot exposure.
Plan for multiple replacement properties if needed. If a single replacement property doesn’t use the full exchange value, structuring the exchange across multiple replacement properties can absorb the remaining proceeds and debt requirement rather than leaving a boot gap.
Know your number before you’re under contract. A quick calculation — comparing relinquished sale price and payoff debt against a target replacement property’s price and financing — before making an offer avoids an unpleasant boot surprise at closing.
Calculating Boot: A Simplified Example
Say you sell a relinquished property for $2,000,000 with a $1,200,000 mortgage payoff, leaving $800,000 in net equity. If you purchase a replacement property for $1,800,000 with $1,000,000 in new financing (contributing $800,000 in equity), you’ve reduced your debt by $200,000 ($1,200,000 minus $1,000,000) without offsetting it with additional cash beyond your existing equity. That $200,000 debt reduction is boot, taxable to the extent of your realized gain on the original sale — even though you reinvested all of your cash equity.
This is a simplified illustration; actual boot calculations also account for exchange expenses, adjusted basis, and other factors specific to your transaction. Run your specific numbers with your CPA before relying on a general example.
When a Partial Exchange Is a Deliberate Choice
Sometimes boot isn’t a mistake — it’s a deliberate decision. An investor might intentionally take some cash out of an exchange to cover a specific need, accepting the tax on that portion while still deferring gain on the reinvested majority. This can make sense when the tax cost of the boot is outweighed by a genuine need for liquidity. The key is making that trade-off knowingly, with the actual tax cost calculated in advance, rather than discovering unexpected boot after closing.
Frequently Asked Questions
What is boot in a 1031 exchange? Any value received in the exchange that isn’t like-kind replacement real estate — most commonly cash or debt reduction — which is taxable to the extent of realized gain even though the rest of the exchange still qualifies for deferral.
Does a mortgage payoff count as boot? It can. If the debt on your replacement property is less than the debt that was paid off on your relinquished property, and you don’t offset the difference with additional cash, the reduction in debt is generally treated as taxable boot.
Can I do a partial 1031 exchange on purpose? Yes. Some investors deliberately take cash out of an exchange, accepting tax on that portion while deferring gain on the rest — this is a legitimate strategy when the tax cost is calculated and accepted in advance, rather than an accidental result of under-reinvesting.
How do I avoid boot in my 1031 exchange? Generally, by ensuring your replacement property’s purchase price and financing are equal to or greater than your relinquished property’s sale price and payoff debt, or by contributing additional cash to offset any shortfall.
Is boot always cash? No. Boot can be cash, debt relief (mortgage boot), or non-like-kind property received as part of the transaction. Debt-related boot is the type that most often surprises investors who assume “I reinvested all my cash” automatically means no boot.