What Does Porting a Mortgage Mean?

Porting is transferring your current mortgage deal to a new property when you move home — keeping the same interest rate, the same product features and the same terms, rather than paying off your mortgage and taking out a brand-new one. If you’re part-way through an attractive fixed rate, porting is how you take that rate with you instead of losing it.

The appeal is twofold: you keep a rate that may be far better than anything on the market today, and you usually avoid the early repayment charge you’d otherwise pay for leaving your deal early. Most mortgage deals are portable (check your original mortgage offer), and porting has become much more common as ERCs on fixed deals have risen. But — and this is the part most people miss — “portable” doesn’t mean “guaranteed.”

How Porting Works — the Catch Everyone Misses

Here’s the single most important thing to understand: you can’t just pack your mortgage in a suitcase and take it with you. Porting transfers the product — the rate and deal — not the loan itself. Legally, your old mortgage is redeemed (paid off) and you take out a new one on the new property at the same terms. And because it’s technically a new mortgage, you must re-apply and re-qualify.

The broad steps: check your mortgage offer confirms the deal is portable → get a decision in principle from your lender → submit a full application (affordability, credit, valuation) → on approval, complete the sale and purchase, typically on the same day. Start to finish, a straightforward port usually takes one to three months, longer if you’re also borrowing more.

Borrowing the Same, More, or Less

How porting works in practice depends entirely on how much you need to borrow on the new home versus what’s left on your current mortgage:

Porting and Early Repayment Charges

Avoiding the early repayment charge is one of the main reasons people port — but the detail matters:

• Like-for-like porting (same loan amount) generally means no ERC, because you’re not actually repaying any of the balance early.
• Downsizing / borrowing less means part of your loan is repaid early, so an ERC may apply to that portion only (typically 1–5% of the amount redeemed). Some lenders refund it if your new mortgage completes within a set window — always ask before you commit.
• Additional borrowing doesn’t usually attract an ERC on the ported part, but the top-up is a new product with its own future ERC period.

ERCs are usually a percentage of the balance that steps down over the deal (e.g. 5% year one, 4% year two, and so on), so exactly when you move affects the cost. This is precisely the sort of sum where getting the numbers right before you act saves real money.

Timing and the Grace Period

Porting has a timing dimension people often overlook. Most lenders expect you to complete the sale of your old home and the purchase of your new one on the same day — a simultaneous port. But life isn’t always simultaneous:

• Non-simultaneous porting (selling first, buying shortly after) isn’t offered by every lender. Where it is, you may have to pay the ERC on sale and reclaim it once you complete the purchase within a set period.
• The grace period varies hugely — some lenders allow only around 30 days between redeeming the old mortgage and completing the new one; others are far more generous (Nationwide, for example, allows up to 180 days, after which the ported rate is lost) (as of 2026 — confirm current).

What If Your Port Is Declined?

It happens more than you’d expect, because porting is a fresh application against current criteria. Common reasons: your income has fallen, you’ve taken on new debt, your credit score has dipped, the loan-to-value on the new property doesn’t fit, or the lender’s rules have simply tightened since you borrowed. If it happens:

• Ask the lender why — and whether it’s something fixable (e.g. paying down a debt, waiting for a blip to clear).
• Request a review if you think the decision is wrong, or escalate to the Financial Ombudsman if you believe you’ve been treated unfairly (lenders have, in the past, been challenged for applying overly strict checks to ports).
• Consider a fresh remortgage with a new lender — you’d likely pay the ERC and exit fees on your current deal, plus new setup costs, but it may still be the only or best route.

A broker is genuinely valuable here, because they can assess before you apply whether your port is likely to succeed, and line up alternatives so a decline doesn’t derail your move.

Porting vs Remortgaging — Which Is Cheaper?

This is the decision that actually matters, and the answer isn’t always “port.” Here’s the key insight most people miss: porting keeps your old rate — which is great if that rate is low, but it also means that even if you’ve built up equity and dropped an LTV band, you won’t automatically get a cheaper deal, and any additional borrowing is at today’s rates anyway.

Because the maths depends on your exact rate, ERC, how much you’re borrowing and today’s deals, this is a genuine “run the numbers” decision — and exactly where a whole-of-market broker earns their keep, comparing a port against remortgaging across the market (including ERCs) to find the cheaper path.

Frequently Asked Questions