Porting Your Mortgage Explained

If you're moving home partway through a mortgage deal, you don't necessarily have to give it up. Many mortgages are "portable", letting you carry your existing rate over to your new property.

Porting means transferring your current mortgage deal — including its interest rate and terms — to a new home when you move. It can help you avoid early repayment charges and keep a good rate, but it isn't automatic: your lender re-assesses your application as if it were new.

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Key Takeaways

• Porting transfers your existing rate and terms to a new property when you move.
• It can help you sidestep early repayment charges on your current deal.
• Your lender re-underwrites the application — approval is not guaranteed.
• Porting can fail if affordability, the new property, or timing don't line up.

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What Does Porting a Mortgage Mean?

Porting is the process of taking your current mortgage product with you to a new home. Rather than paying off your existing mortgage and starting a brand-new one, you keep the same deal — the interest rate, the terms, and often the same lender — but secured against your new property.

The appeal is straightforward. If you're locked into a fixed rate with an early repayment charge (ERC), porting can let you move without triggering that charge. And if your current rate is better than what's available now, keeping it can save money.

Whether your mortgage can be ported depends on your product. Most are portable in principle, but the terms vary, so check your paperwork or ask your lender.

Porting Isn't Automatic — You're Re-Assessed

This is the part borrowers most often misunderstand. Porting isn't simply picking up your mortgage and dropping it onto a new house. Your lender treats it much like a fresh application and will re-underwrite it, checking:

• Affordability. Your income, outgoings and circumstances are re-assessed against current lending rules — which may be stricter than when you first borrowed.
• The new property. It must be acceptable security, so the lender will value it and may decline unusual or non-standard properties.
• The loan amount and loan-to-value. If you're borrowing more, you'll usually need a top-up loan, potentially on a different rate.

Because affordability is re-checked, it's worth understanding what you could borrow now before you commit to a move:

Borrowing More or Less When You Port

Few people move to a home that costs exactly the same as their old one, so porting often involves adjusting the loan.

• Buying a more expensive home? You port your existing balance on its current rate and take an additional "top-up" loan for the extra you need — usually on whatever rate the lender offers at the time. You end up with two sub-accounts on potentially different rates and end dates.
• Buying a cheaper home? You may only need part of your existing loan. Reducing the balance can sometimes trigger a partial early repayment charge, so check the detail.

If you're weighing up the whole moving-with-a-mortgage question, our guide on what happens if you have a mortgage but want to move covers the wider picture.

Timing: The Trickiest Part

Porting usually requires your sale and purchase to complete at the same time, because the deal moves directly from one property to the other. That's simple in theory but harder in a chain, where delays are common.

Some lenders offer a short window to port after redeeming your old mortgage — sometimes a number of days or weeks — which can help if there's a small gap between selling and buying. Beyond that window, you may lose the ability to port and face the ERC after all. Always confirm your lender's specific rules early.

When Porting Falls Through

Even with a portable mortgage, porting can fail. The most common reasons are:

• Failing affordability re-checks, especially if your income has dropped or lending rules have tightened.
• The new property being unacceptable to the lender.
• Timing gaps that exceed the lender's porting window.
• A change in circumstances, such as a new job or self-employment, that makes the lender cautious.

If porting isn't possible, remortgaging to a new lender is the usual alternative. It's worth comparing that route too — our guides on whether you can remortgage early and how easy it is to switch mortgages explain the options and costs.

Will I definitely be able to port my mortgage?

No. Even portable mortgages are re-underwritten, so approval depends on current affordability and the new property being acceptable. Check with your lender before relying on it.

Does porting avoid early repayment charges?

It can. Porting your existing balance typically avoids the ERC, but repaying part of the loan, or failing to port within the lender's window, may still trigger a charge.

Can I borrow more when I port?

Usually yes, via a top-up loan on a separate rate. The extra borrowing is subject to affordability checks and the lender's loan-to-value limits.

Porting can be a smart way to move home without losing a good rate or paying an early repayment charge — but treat it as a fresh application, plan the timing carefully, and have a remortgage as a backup. A broker can confirm whether porting or switching lenders leaves you better off.