Key facts: Porting moves your existing mortgage deal (rate, terms, remaining fix) to a new property. You must re-apply and re-pass affordability — porting is a right to ask, not a right to have. Extra borrowing for a more expensive home is priced at current rates as a separate slice, and early repayment charges are usually refunded or avoided if you complete the port within the lender's window.
How porting actually works
Most fixed and tracker mortgages are technically portable. When you move, the lender re-underwrites you — income, outgoings, credit — and values the new property. Pass, and your existing deal carries over for its remaining term. The part people miss: you're assessed under the lender's current criteria, not the ones you passed originally. Income dropped, gone self-employed, new childcare costs — any of these can sink a port even though you've never missed a payment.
Moving somewhere more expensive
Your ported deal covers the existing balance; anything extra becomes a top-up loan at today's rates. You end up with two slices, potentially with different end dates — a small administrative nuisance that's usually still far cheaper than paying an early repayment charge to leave the original deal. Ask the lender to align end dates where possible, so future remortgaging is clean.
Moving somewhere cheaper
Downsizing can trigger partial early repayment charges if the new loan is smaller than the old one — you're "repaying" the difference. Whether that's material depends on your ERC schedule and how much you're reducing. Sometimes completing the port and using your annual overpayment allowance is cheaper than a straight reduction.
Porting vs remortgaging
Porting wins when your current rate beats today's market and the ERC is meaningful. Remortgaging wins when market rates have fallen below your deal, when your lender declines the port, or when the new property doesn't fit their criteria. Run both numbers before assuming — our remortgage guide covers the other side, and a broker will compare the true costs in minutes.
Planning a move mid-fix?
Timing matters: ports generally must complete within a set window (often 30–90 days between redemption and new completion) to preserve the deal or reclaim the ERC. A broker can sequence the sale, purchase and port so nothing lapses. Get matched with a mortgage broker through Nesto — free, no obligation.
Frequently asked questions
Can every mortgage be ported?
Most deals are portable on paper, but you must re-pass affordability and the property must meet criteria. Check your offer document or ask your broker.
Can I port and borrow more?
Yes — the extra is a separate slice at current rates, subject to affordability on the whole amount.
Will I pay early repayment charges if I port?
Usually not, if the port completes within the lender's window — some lenders charge upfront and refund on completion.
What if my lender refuses the port?
You can remortgage to another lender — weighing the ERC against the savings — or in some cases challenge the decision with better-packaged evidence. A broker will pressure-test both routes.