Loan Assumption Explained: Buying Commercial Property With the Seller's Existing Debt

What it is

A loan assumption is exactly what it sounds like: instead of getting your own new financing, you step into the seller's existing loan and take over the remaining balance, rate, and terms. The debt stays on the property. You just become the new borrower.

How it plays out in retail net lease

Most of the time you buy a net-lease property, you bring your own money and your own loan. Assumption is the exception, and it usually shows up for one reason: the seller locked in a rate that's better than what you'd get today.

Here's how I look at it. When rates jump, a loan written a few years ago at a lower fixed rate becomes an asset in its own right. If a seller has, say, five years left on a low-rate, non-recourse loan, taking that over can be worth real money to you — sometimes more than the building's cap rate suggests on paper.

The mechanics: the loan doesn't just transfer because you both want it to. The lender has to approve you. On a lot of commercial and CMBS loans there's an assumption clause that spells out the process — you apply, they underwrite you like any borrower, and they charge a fee (often a percentage of the loan balance) to sign off. On single-tenant net-lease deals, the tenant and the lease usually stay put, which makes the underwriting cleaner. The lender already knows the income story.

What to watch for

• The rate is only good if there's real term left. A great rate with 14 months to maturity is a problem you inherit, not a gift. You'll be refinancing into whatever the market is soon enough.
• Assumption fees and legal costs. The lender's fee, their attorney, your attorney — it adds up. Bake it into your price, not your feelings.
• You may have to match, not lower, the debt. If the existing loan is smaller than what you'd normally borrow, you're bringing more cash to close. If it's larger than you want, you can't just pay it down without permission.
• Lender approval is not a formality. They can decline you, or require a net-worth or liquidity profile you don't have. Get a real read early.
• Defeasance and prepayment language. Assumable loans often carry ugly prepayment terms. That low rate can come with a very expensive exit if your plans change.
• Timeline. Assumptions frequently take longer to close than a fresh loan. Build that into your contract.

How to use it to your advantage

Treat the loan as part of what you're buying, because it is. When I underwrite an assumable deal, I run it two ways: the price with the existing debt, and the price as if I had to finance it new today. The gap between those two is the value of the loan. Sometimes it's meaningful enough to pay up a little on price and still come out ahead on cash flow.

Then get the actual loan documents — not the summary, the documents — in front of a lawyer early. The assumption clause, the fee, the prepayment terms, the reserve requirements. That's where the deal is really priced. Use your due diligence window to get the lender's approval moving in parallel, so a "no" from underwriting doesn't blow up your closing.

Best case, worst case

Best case:

• You inherit a below-market fixed rate with years of term left.
• The loan is non-recourse and the tenant is stable, so your risk is contained.
• Your day-one cash flow beats anything you could arrange with new debt.

Worst case:

• The rate looks good but the term is short and the prepay is brutal.
• Fees and a slow lender approval eat the advantage you were chasing.
• You get underwritten, declined, and lose time you can't get back.

The honest takeaway: a good assumable loan can genuinely change the math on a deal, but it rewards buyers who read the fine print and punishes the ones who fall in love with the rate. Do the two-way underwrite, get counsel on the documents, and confirm the lender wants you before you commit.

This is general education, not investment, tax, or legal advice — verify everything independently with your own advisors before acting.