Mortgage Porting Explained: Move House Without Losing Your Rate in 2026

What Porting Actually Does

If you're partway through a fixed-rate, tracker, or discounted mortgage deal and want to move house, leaving that deal early would normally trigger an Early Repayment Charge (ERC) — often a percentage of the outstanding balance, sometimes several thousand pounds. Porting is the mechanism that lets you avoid this: instead of redeeming the mortgage and starting fresh, you carry the existing product — including its interest rate and remaining term — across to the new property.

Crucially, porting is a feature of the mortgage product, not a universal right — check your mortgage offer or ask your lender whether your specific deal is portable, since not all products include this option.

Why It's Not Automatic

Even though you're keeping the same lender and the same underlying deal, porting still requires the lender to reassess the whole application:

• Affordability: your income, outgoings, and existing debts are reassessed against current lending criteria, which may have tightened or loosened since you first took out the mortgage
• Credit history: any changes since your original application — missed payments, new debts, changed employment status — are reviewed
• Property valuation and criteria: the new property must meet the lender's current criteria (type, construction, location, valuation)

This means a long-standing customer with a strong payment history isn't guaranteed approval — if your circumstances have changed (for example, you've become self-employed, taken on other debt, or your income has dropped), the lender can decline the ported application even though it's the same lender and same original deal.

Porting With Additional Borrowing

Many house moves involve buying a more expensive property, meaning you need to borrow more than your existing mortgage balance. In this situation:

Some lenders keep these as genuinely separate sub-accounts (sometimes with slightly different end dates), while others blend the rates into a single effective rate for the whole mortgage. Ask your lender directly how they structure a porting-plus-further-borrowing case, since the practical effect on your monthly payment and overall cost can differ between approaches.

When Porting Is Worth the Hassle

Porting is most valuable when:

• Your current rate is meaningfully below current market rates — the ERC-avoidance and rate-retention benefit is largest here
• You're still well within the fixed or discounted period, where the ERC would otherwise be significant
• Your circumstances haven't materially changed since the original application, making a successful reassessment more likely

It's less valuable, and sometimes not worth pursuing, if:

• Your current rate is similar to or worse than what's available on the open market — in which case remortgaging to a new deal (accepting the ERC if applicable) might leave you better off overall
• You're near the end of your current deal anyway, when the ERC may be small or non-existent

What Happens If the Ported Application Is Declined

If the lender won't approve porting to the new property — due to changed affordability, credit issues, or the property not meeting criteria — your realistic options are:

1. Look for a different property that better fits the lender's criteria
2. Apply to a different lender, which typically means paying the Early Repayment Charge on your current deal to redeem it, then taking a new mortgage product elsewhere
3. Delay the move until your circumstances improve enough to pass the reassessment

Practical Steps

1. Check your current mortgage offer document or contact your lender to confirm whether your product is portable.
2. Get a clear, written figure for your current Early Repayment Charge, so you know the cost of not porting as a comparison point.
3. Start the porting conversation with your lender early in your house-buying process, ideally before making an offer, since you need underwriting approval alongside your usual mortgage application timeline.
4. If additional borrowing is needed, ask specifically how the lender structures the blended rate or sub-accounts, and compare the total cost against simply remortgaging fresh with a different lender.
5. Have a backup plan (a different lender's product, or accepting the ERC) in case the ported application doesn't go through — timing a house purchase around an uncertain mortgage decision carries risk, so build in contingency where possible.