The Forgotten Half of Every 1031 Exchange: Your Client’s Mortgage

Ask an advisor what makes a 1031 exchange work, and the answer comes fast: reinvest all the proceeds. That is true, but it is only half the rule. The part advisors forget, and the part that quietly derails exchanges, is the mortgage.

To defer all gain, an investor must do two things: reinvest all net cash from the sale, and replace all debt that was paid off at closing. The IRS treats equity and debt as separate ledgers. A shortfall on either one creates taxable boot.

Walk through a simple example. Your client sells a property for $1,000,000. A $400,000 mortgage is paid off at closing, leaving $600,000 of net cash with the qualified intermediary. Full deferral requires acquiring replacement property worth at least $1,000,000, and that $1,000,000 must consist of $600,000 in cash plus $400,000 in new debt. If the client buys an $800,000 property with $600,000 down and $200,000 of debt, the $200,000 of unreplaced debt is mortgage boot. It is taxable, even though every dollar of cash was reinvested.

This is where DSTs enter the picture, because the debt math works differently across DST structures.

Some DST offerings are levered, meaning the trust carries a loan. When your client subscribes to a levered DST, their pro rata share of the trust's debt generally counts toward replacing the debt paid off on the relinquished property. The client gets debt replacement without personally signing for a new loan.

Other DSTs are all-cash and debt-free. No trust-level loan means no debt to allocate. If your client's exchange has $400,000 of debt to replace and they place all $600,000 of cash into a debt-free DST, the debt ledger is short by $400,000. That is boot, and it does not matter that the DST was a fine investment.

Debt-free is not a flaw. It is a design choice with a real advantage: no lender, no refinancing risk, no loan covenants constraining the trust. But it only works for the client whose debt situation fits. A client who owned their relinquished property free and clear has no debt to replace, so a debt-free DST is a clean match. A client carrying significant leverage needs a plan for the debt half, and that plan has to exist before the identification deadline, not after.

Advisors have a few standard ways to handle this:

First, split the proceeds. Put the cash equity into a debt-free DST and the debt-replacement portion into a levered DST or a debt-financed whole property. The DST can be sized to the cash, which helps avoid overfunding.

Second, add cash at closing. An investor can replace debt with additional cash from outside the exchange. This works when the client has the liquidity, and the added cash simply becomes part of the reinvestment.

Third, accept a partial exchange. Sometimes the math does not close and the client chooses to pay tax on the boot rather than force an unsuitable purchase. A planned partial exchange beats a surprised one.

A few practical points to keep in the file for every 1031 client:

Ask about the mortgage at the first meeting, not at day 40. The debt number shapes the entire replacement strategy, and surprises here are the most expensive kind.

Confirm how the DST treats debt before naming it in the identification letter. The PPM describes whether the offering is levered or all-cash and how trust-level debt is allocated. Do not assume a DST will solve the debt problem; verify it.

Watch pre-sale refinancing. If a client pulls cash out with a new loan just before selling, the IRS may treat the cashed-out proceeds as taxable boot rather than exchange funds. Flag this early and send the client to their tax advisor before anything is signed.

Keep the qualified intermediary in the loop on the split. When proceeds are divided between a debt-free DST and a levered replacement, the QI wires multiple directions and tracks both ledgers. They need the plan before closing documents are drawn.

Most exchange postmortems focus on the property: the deal that fell through, the identification that was too narrow. But plenty of failed exchanges had a perfectly good replacement property and still produced a tax bill, because nobody planned for the mortgage. The debt half of a 1031 exchange is unforgiving, but it is also predictable. Ask the question early, and it is a planning exercise. Skip it, and it is a tax bill.

This article is educational content only and is not tax or legal advice. Investors should consult their tax advisor and qualified intermediary before acting.