Porting your mortgage

Porting is the process of moving your existing mortgage — including the current interest rate, remaining term, and outstanding balance — from your current property to a new one. It’s not a legal right; it’s a feature offered by many (but not all) lenders.

When you port, you’re essentially applying for the same mortgage on a different property. The lender will still reassess your affordability and value the new property, so approval isn’t guaranteed.

If your new property costs more than your current one, you’ll need to borrow extra on top of your ported mortgage. This additional borrowing is usually arranged as a separate loan (sometimes called a “top-up”) which may be at a different interest rate.

For example, if you’re porting a £200,000 mortgage at 3.5% and need to borrow an extra £80,000, the top-up might be at the lender’s current rate of 4.5%. You’d effectively have two loans running in parallel on the same property.

The lender will assess your affordability for the total borrowing (£280,000 in this case). If the numbers don’t work, they may decline the additional borrowing even if they’re happy to port the original amount.

Start by checking your original mortgage offer document — it should state whether porting is allowed under the product terms. If you can’t find it, call your lender’s customer service line and ask directly.

Your broker can also check this for you and, if porting is available, assess whether it’s actually the best option compared to the alternatives on the open market.