Porting a mortgage means transferring an existing mortgage deal, with its rate and terms, from one property to another when moving home. The same product continues on the new property, which can avoid paying an early repayment charge.
In one line: Porting a mortgage carries an existing deal and its rate across to a new home when moving.
How porting a mortgage works
Porting keeps the existing rate but requires a fresh affordability and property assessment, so it is not guaranteed. The lender treats it like a new application against the new home.
On a 160,000 GBP loan fixed at 3.5% with two years left, porting avoids a possible 4,800 GBP early repayment charge while keeping the lower rate. If the new home costs more, the extra borrowing is usually taken on a separate product at current rates.
If the move falls through or the new property fails the lender's checks, porting can be refused even when the deal is technically portable.
Porting a mortgage vs remortgaging
Porting moves the same deal to a new property and keeps the existing rate. Remortgaging replaces the deal entirely, usually on the same property, with a new lender or product.
Porting is the route most likely to sidestep an early repayment charge when moving home.
Primary source: FCA: Mortgages and home finance