Is subject-to legal? What the due-on-sale clause really lets a lender do

With the 30-year mortgage rate at 7.40% the week of October 8, 2026, and about half of all outstanding mortgages carrying a rate under 4% (FHFA, second quarter of 2026), a seller's old loan can be worth more than the house's discount. That's why subject-to searches keep climbing. It's also why the first question everyone asks is the same: is this legal?

Here's the short version, then the law itself, quoted, so you can see exactly where the risk sits. This is not legal advice. Use a real estate attorney in your state before you sign anything.

What federal law actually says

The due-on-sale clause comes from the Garn-St Germain Act, 12 U.S.C. 1701j-3. It lets a lender put a clause in the mortgage, and enforce it, that allows the lender, "at its option," to declare the whole debt due if all or part of the property, or an interest in it, is sold or transferred without the lender's prior written consent.

Two things in that sentence matter.

It's an option, not a duty. The law doesn't require a lender to call the loan. It lets them.

It's a contract right, not a crime. Nothing in the statute makes a subject-to purchase illegal. What a subject-to deal usually does is give the lender the right to demand payment in full. If nobody pays, that's a foreclosure on the seller's loan.

The nine transfers the law protects

The statute lists transfers where a lender may not use the clause on a home with fewer than five units. Paraphrased:

1. A second lien that doesn't transfer the right to live there.
2. A lien for household appliances.
3. A transfer on the death of a joint tenant.
4. A lease of three years or less with no option to buy.
5. A transfer to a relative after the borrower dies.
6. A transfer where the borrower's spouse or children become owners.
7. A transfer to a spouse in a divorce or separation.
8. A transfer into a living trust where the borrower stays a beneficiary.
9. Any other transfer federal regulators exempt by rule.

A sale to an investor isn't on the list. Neither is a transfer to an LLC.

What the loan owners tell their servicers

A large share of mortgages are owned or backed by Fannie Mae, Freddie Mac or a government agency, and their rules for servicers are public.

Fannie Mae's servicing guide names a purchase "subject to" the mortgage as a transfer of ownership for due-on-sale purposes. Unless the transfer is exempt, it says the servicer "must accelerate the debt" after the required notices.

Fannie does exempt some transfers to an LLC, but only when Fannie bought the loan on or after June 1, 2016 and the original borrower controls the LLC or owns most of it. That's built for a homeowner moving their own house into their own LLC. It doesn't cover an investor taking title.

FHA loans work differently. HUD's handbook says a servicer has to ask HUD's approval before calling an FHA loan for a transfer, and lists cases where it may not call it at all, including when the seller keeps an ownership interest. FHA loans are also formally assumable, which is a different path from subject-to. Here's how assumptions compare.

How often loans actually get called

We looked for a number. There isn't one. No regulator, no Fannie Mae or Freddie Mac report, no HUD or VA publication we could find says how often servicers call a loan after a subject-to sale.

You'll hear "it almost never happens" in every subject-to course. Maybe so. But it's an anecdote, not a statistic. And the incentive runs the wrong way for you when rates rise: a 3% loan is worth less to whoever owns it when new loans pay 7.40%. Plan for the call.

State laws that add rules

Federal law isn't the only layer. A few states regulate subject-to, wraps and deals with owners in trouble directly.

Maryland (from October 1, 2025) and Oregon (registration from July 1, 2025) also passed wholesaling laws that require disclosures, which matters if you plan to assign a subject-to contract. Other states have foreclosure-rescue and equity-skimming laws written long before subject-to was a trend. Your attorney will know yours.

What the seller is risking

This part gets skipped. After a subject-to sale, the loan is still in the seller's name. If the payments stop, it's the seller's credit and the seller's foreclosure, on a house they no longer own. If the lender calls the loan, the seller's name is on the demand letter.

That's why the laws above lean so hard on disclosure. An owner who understands the deal, in writing, with time to back out, is the deal that holds up. And it's why the sellers who say yes tend to be owners who are already behind: for them, the alternative is the foreclosure itself.

Where subject-to sellers come from

Owners behind on their payments show up in public records, in the foreclosure filings. Federal rules keep a servicer from filing until the loan is more than 120 days behind, so a filing means months of missed payments and a clock that's running.

Those owners sell. Across the 99 counties where we could measure them, about 13 of every 100 owners with a foreclosure filing sold off-market within 12 months of the filing, against about 1.2 of every 100 houses picked at random. The timing differs by county, and in most counties the busiest stretch came after the first three months. Here's how to find them, and the free tool below shows when foreclosure filings sold in your county.