Portable Mortgages in the U.S.: How Taking Your Rate With You Could Reshape Housing

What are portable mortgages and why are they being studied?

The housing finance regulator that oversees Fannie Mae and Freddie Mac is studying whether portable mortgages could help loosen up a very tight U.S. housing market.[empower.com] A portable mortgage would let a homeowner transfer their existing loan — including its interest rate — from one property to another when they move.

Empower explains the basic goal: reduce the housing market’s “lock-in effect,” where owners with very low pandemic-era rates feel stuck because selling would mean taking on a much higher rate on the next home.[empower.com] With average 30‑year fixed mortgage rates now in the low‑6% range, many owners see moving as a financial step backward.

According to Empower’s research, nearly half (48%) of current mortgage holders have rates below 4%, and almost three-quarters (74%) are below 6%.[empower.com] That creates a huge gap between existing loans and what a new buyer — or the same owner moving — would pay today.

How a portable mortgage could work in practice

In Empower’s example, consider a borrower selling a $400,000 home with a remaining balance of $200,000 on a 3% fixed-rate mortgage.[empower.com] Under a portable structure, that borrower could sell the home, then carry that same $200,000 loan and 3% rate to a new property.

If the new home costs exactly $400,000 and the borrower rolls over the $200,000 loan plus their equity, the math is straightforward. But most real-world cases will be more complex:

• **More expensive home:** If the next home costs $450,000, the buyer has to cover the extra $50,000. That could come from cash, a second mortgage, or a new first-lien loan, likely at the prevailing market rate.[empower.com]
• **Less expensive home:** If the next home is cheaper than the old one, rules would need to define whether the borrower can keep the full original loan amount, must pay it down, or restructure it.

Portable mortgages are different from **assumable mortgages**, which already exist on some government-backed loans. With an assumable mortgage, a buyer takes over the seller’s existing loan and rate (subject to approval). With portability, it’s the *seller* who takes their own loan to another property instead.[empower.com]

Countries like the U.K. and Canada offer a form of portability, but their systems look different: fixed-rate periods are often five years or less before borrowers refinance, and loans are frequently repriced along the way.[empower.com] That shorter horizon makes it easier for lenders and investors to manage interest-rate risk.

The 30-year fixed and the MBS puzzle

Portable mortgages have never been used in the U.S., in part because the housing system is built around long-term fixed-rate products. The 30‑year fixed-rate mortgage is essentially a uniquely American construct, supported by Fannie Mae and Freddie Mac and the way they package loans into mortgage-backed securities (MBS).[cnbc.com][fhfa.gov]

Fannie and Freddie buy loans from lenders, bundle them into securities, add guarantees, and sell those securities to investors. This process keeps mortgage credit flowing and helps stabilize rates.[fhfa.gov] A key feature of that market is **prepayment behavior** — the fact that homeowners typically pay off their loans when they sell or refinance, which affects how quickly cash flows back to investors.

If many borrowers could keep their old loans when they move, prepayment patterns would change. Empower notes that a shift to portable mortgages could affect how MBS are structured and priced, and how investors value that cash-flow uncertainty.[empower.com] That, in turn, could influence the rates lenders are able to offer.

Any move toward portability would likely require:

• New rules for how portable loans are pooled into securities
• Updated models for prepayment and extension risk
• Clear standards around when and how a loan can be moved, and what happens to any new money needed for the next purchase

These details matter because they determine whether lenders and investors are willing to support the product at scale and at what interest rate.

Who benefits — and who may be left waiting

Advocates argue that portable mortgages could make the real estate market more liquid by letting existing homeowners move more easily without giving up their low rates, freeing up more inventory for new entrants.[empower.com] This could particularly help households that need to move for jobs, family changes, health reasons, or retirement.

But Empower and other commentators also caution that the benefits would be selective.[empower.com][realtor.com]

• **Existing low-rate borrowers** could gain the most, since they’d preserve a below-market rate when relocating.
• **First-time buyers and households without mortgages** would still face current prices and rates on their initial purchase.
• **Move-up buyers without very low existing rates** might see only modest advantages, depending on how portability rules are written.

There are also potential regional effects. Markets with a large share of locked-in owners might see more listings over time if portability takes off, which could gradually ease local supply constraints. But in high-demand areas, added mobility could also support continued price competition, especially if more buyers can bring cheap debt with them.

What borrowers can do now, while policy is in flux

For now, portable mortgages remain an idea under study rather than a product consumers can request. The outcome is uncertain, and even if approved, any rollout would take time as lenders, Fannie Mae, and Freddie Mac adjust systems and investor structures.[empower.com]

In the meantime, Empower points to several tools borrowers are already using to navigate higher rates:[empower.com]

• **Adjustable-rate mortgages (ARMs):** These start with lower initial rates, often in the mid‑5% range recently, in exchange for rate adjustments later.
• **Temporary buydowns:** Builders and some sellers are offering buydowns that reduce the borrower’s rate for the first few years of the loan.
• **Buyer concessions:** More sellers are helping cover repairs, closing costs, inspections, or other transaction expenses.
• **Assumable mortgages:** On some FHA, VA, and other government-backed loans, qualified buyers can take over an existing mortgage and rate, paying the seller for their equity.

Freddie Mac data show that as of November 2025, the average 30‑year fixed mortgage rate was around the mid‑6% range, roughly half a percentage point lower than a year earlier.[freddiemac.gcs-web.com][empower.com] While that’s an improvement from prior peaks, it’s still far above the sub‑3% loans many owners locked in earlier in the decade.

How to think about your own strategy

If you already have a low-rate mortgage, it’s worth regularly reevaluating the nonfinancial reasons you might need to move — job changes, family needs, health, or quality of life — against the cost of giving up that rate.

Portable mortgages, if they emerge, could reduce that trade-off for some households. But they won’t erase broader affordability constraints. Prices remain elevated compared with 2019 levels, and first-time buyers will still need to clear today’s financial hurdles even if more listings hit the market.[empower.com][realtor.com]

For buyers and investors, the key is to treat portability as a *potential* future feature, not a certainty. Focus current decisions on products and strategies that are actually available now, while keeping an eye on how the policy conversation evolves in the years ahead.