Porting Your Mortgage: Keeping Your Rate When You Move House
Porting lets you take your existing mortgage deal, including a fixed rate, with you to a new property instead of paying an early repayment charge. How it works, when the numbers don't add up, and what can still go wrong.
Why porting exists
If you're partway through a fixed-rate (or other discounted) mortgage deal and you sell your home before the deal ends, you'd normally face an early repayment charge (ERC) for exiting the deal early β often a meaningful percentage of the outstanding balance. Porting offers an alternative: rather than repaying the mortgage and triggering the charge, you transfer the existing deal β rate, product, remaining term β to your new property instead.
How porting actually works
| Step | What happens |
|---|---|
| 1. Apply to port | Contact your existing lender before completing your sale/purchase |
| 2. Fresh assessment | Lender reassesses affordability, credit history and suitability of the new property as security |
| 3. Approval (or not) | If approved, the existing rate and remaining term transfer to the new mortgage |
| 4. Additional borrowing (if needed) | Arranged as a separate new portion, potentially at a different, current-market rate |
| 5. Completion | The port typically needs to complete within a lender-set timeframe of your sale and purchase |
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Open Mortgage calculatorThe crucial catch: it's not automatic
A common misconception is that porting is a guaranteed right simply because you're keeping the "same" mortgage. In reality, your lender treats a ported mortgage as a new lending decision in terms of affordability and credit assessment β even though the rate itself may stay the same. If your financial circumstances have changed since you first took out the mortgage β lower income, a change in employment type (for example, moving from employed to self-employed), new debts, or a change in credit history β you might not pass this fresh assessment, even if you desperately want to keep your existing rate.
If porting fails for this reason, you could be left in the position of repaying your existing mortgage in full (triggering the early repayment charge after all) and needing to arrange completely new mortgage finance, often at short notice and potentially on less favourable terms β a genuinely stressful scenario worth planning for.
What happens if you need to borrow more
Moving to a more expensive property often means needing to borrow more than your existing mortgage balance. In this case, the additional amount is typically arranged as a separate new portion of the overall mortgage β assessed and priced based on current market conditions and rates at the time, rather than automatically getting the same rate as your original, older deal. This means your overall blended monthly payment can still increase, even though the original portion of your borrowing keeps its favourable existing rate.
Not every mortgage is portable
Portability is a specific feature of a mortgage product, not a universal right across every deal β always check your specific mortgage's terms and conditions. Even among portable products, the detailed conditions (including any timeframe within which the port must complete relative to your sale and purchase) vary meaningfully between lenders.
The timing risk
Many lenders set a specific window β for example, a defined number of months β within which the sale of your existing property and purchase of the new one must both complete for the port to be honoured. If you're in a slow-moving property chain, there's a genuine risk that delays push you past this window, potentially losing the ability to port and facing the early repayment charge regardless. This is worth checking and factoring into your planning if your chain looks likely to be complicated or slow.
uk-mortgage-affordability-guide-2026Porting vs remortgaging: which is actually better?
Porting is most clearly worthwhile when:
- Your existing rate is meaningfully better than current market rates for an equivalent new deal.
- You would otherwise face a significant early repayment charge by exiting the deal early.
- Your financial circumstances remain broadly similar to when you first took out the mortgage, giving you confidence you'll pass the fresh assessment.
A fresh remortgage (potentially with a different lender) might be the better route when:
- Current market rates are actually more competitive than your existing deal β in which case there's little benefit to preserving the old rate.
- Your borrowing needs have changed substantially, making a full remortgage a cleaner way to restructure the whole loan.
- You're unsure you'd pass a fresh affordability assessment with your existing lender, and want to explore options more broadly across the market rather than being tied to one lender's specific criteria.
Practical steps
- Check whether your specific mortgage product is portable, and note any time-limit conditions on completing the port.
- Contact your lender early in your moving process β porting requires a fresh application and assessment, which takes time.
- Compare your existing rate against current market rates to confirm porting is actually the financially better option, rather than assuming it automatically is.
- Prepare for the possibility porting could be declined, and have a contingency plan (a broker conversation about alternative mortgage options) in case your circumstances have changed since your original application.
- Factor in chain timing risk if you're worried about missing the porting completion window.
Frequently asked questions
What does it mean to 'port' a mortgage?
Porting means transferring your existing mortgage deal β including its current interest rate, whether fixed or otherwise, and its remaining term β to a new property when you move house, rather than repaying your existing mortgage in full and taking out an entirely new one, which would typically trigger an early repayment charge if you're still within a fixed or discounted deal period.
Does porting mean I automatically keep my exact monthly payment?
Not necessarily β while the interest rate and remaining term generally transfer, if the new property costs more than your old one and you need to borrow more, the additional amount is usually arranged as a new, separate part of the mortgage, often at a different (potentially higher, since it's a new lending decision at current rates) interest rate β so your overall monthly payment can change even though the original portion keeps its original rate.
Do I need to reapply for the mortgage when porting?
Yes β porting is not automatic or guaranteed; you generally need to go through a fresh affordability and credit assessment as if applying for a new mortgage, since your lender needs to confirm you can still afford the mortgage and that the new property is suitable security, even though you're keeping the same underlying rate and product.
Can porting fail even if I want to keep my current rate?
Yes β if your income, credit history, or overall financial circumstances have changed since you took out the original mortgage (for example, reduced income, a change in employment status, or new debts), you might not pass the fresh affordability assessment required for porting, in which case you could be left needing to repay the original mortgage in full (potentially triggering an early repayment charge) and arrange completely new finance instead.
Can I port a mortgage if I'm buying a cheaper property?
Generally yes, provided you still pass the lender's affordability assessment β but be aware some products may not allow a straightforward partial reduction without adjustment, and it's worth checking the specific terms, since porting rules and any conditions attached can vary between lenders and products.
Does porting work the same way for every type of mortgage deal?
No β not every mortgage product is portable, and even among those that are, the specific terms and conditions (including any timing windows around when the port must be completed relative to selling your existing property) vary between lenders and products, so check your specific mortgage's terms rather than assuming porting is universally available or works identically across all lenders.
Is there a time limit on completing a port?
Many lenders impose a specific timeframe within which you must complete the sale of your existing property and purchase of the new one for the port to be honoured β if your move takes longer than this window (for example, due to a chain delay), you could risk losing the ability to port and facing an early repayment charge instead, so it's worth checking this timeframe carefully if you're in a slow-moving chain.
Should I always try to port rather than remortgage when moving?
Not necessarily β porting is generally most attractive when your existing rate is meaningfully better than current market rates and you'd otherwise face a significant early repayment charge, but if current market rates are actually more competitive than your existing deal, or your borrowing needs have changed substantially, a fresh remortgage (potentially with a different lender) might be a better overall option β compare both routes rather than assuming porting is automatically best.
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