Financing issues

Most investors know a 1031 exchange has a value rule: buy something worth at least as much as you sold. Fewer know it has a debt rule that stands right beside it, and the debt rule is where clean-looking exchanges quietly generate tax. Your replacement property’s mortgage generally has to equal or exceed your old property’s mortgage, and if you want to pull cash out by refinancing, when you do it decides whether it is fine or fatal.

The debt rule: replace your mortgage, not just your equity

To fully defer your gain, two things have to match or go up: the value of what you buy, and the debt on it. The replacement property’s price must equal or exceed the sale price of the old one, and the new mortgage must equal or exceed the old mortgage. This comes from Section 1031(b), which taxes any gain to the extent you receive money or debt relief in the exchange, and shedding debt counts as receiving money.

An example makes it concrete. Sell a rental for $800,000 that carried a $500,000 mortgage. To fully defer, your replacement must cost at least $800,000 and carry at least $500,000 of new debt. Buy a $700,000 property with a $300,000 loan, and you have fallen short on both value and debt, and the shortfall, especially the $200,000 of debt you shed, is taxable mortgage boot even though no cash changed hands.

Full deferral requires replacing both value and debt: the new property must cost at least as much as the old sold for, and the new mortgage must equal or exceed the old one.

The cash cure for a debt shortfall

There is a way to defer fully while carrying less debt: add cash. If your replacement would carry $200,000 less mortgage than your old property, you can put $200,000 of your own cash into the purchase to make up the gap, and the mortgage boot disappears. The IRS lets cash you add offset debt you shed.

This is the standard move for an investor deliberately deleveraging, trading a high-mortgage property for a lower-mortgage one while still deferring. The important constraint runs the other way: cash added into the deal is trapped. Once in, you cannot pull it back out during the exchange without creating cash boot, so the added cash becomes locked-in investment. Debt is measured at closing, so financing has to be finalized in advance to know whether you have a gap to cover.

You can replace less debt without triggering boot by adding your own cash to cover the gap, but cash you add into the exchange is trapped and cannot be pulled back out tax-free.

The refinance trap: timing is everything

Here is the move that gets investors into trouble: refinancing to pull cash out around the exchange. The rule splits sharply on timing.

Refinancing the old property before the exchange, to extract cash right before you sell, is dangerous. The IRS can treat the pre-exchange cash-out as an attempt to pull equity out tax-free that the exchange would otherwise defer, and recharacterize it as taxable boot. The defense, if you must refinance before, is a genuine business purpose independent of the exchange, a rate reduction you had been pursuing for months, documented, but it is a risky position.

Refinancing the replacement property after the exchange closes is generally fine. Once you have taken title and completed the exchange, a later refinance looks like an ordinary decision about managing your new investment, and you remain economically responsible for the new debt. Most advisors still suggest waiting six to twelve months after closing before pulling cash out, to make clear the refinance is a separate decision and not part of the exchange. So the rule of thumb is simple: do not refinance to cash out right before an exchange; wait until well after.

Refinancing to pull cash before an exchange can be recharacterized as taxable boot, while refinancing the replacement property months after closing is generally safe.

The bottom line

• Full deferral requires replacing both value and debt: equal-or-greater price and equal-or-greater mortgage.
• Debt you shed is taxable mortgage boot, even with no cash received.
• You can cure a debt shortfall by adding cash, but added cash is trapped in the exchange.
• Refinancing to pull cash before the exchange can be recharacterized as taxable boot.
• Refinancing the replacement property months after closing is generally safe.

For how the shortfall is taxed, read boot. For deliberately trading down, see partial exchanges. For the full picture, start at the 1031 exchanges and exit planning hub.

Last verified August 2026.