Selling your home does not automatically mean saying goodbye to your current mortgage deal. That matters when you are sitting on a low fixed rate and today’s rates look far less attractive. So, what is mortgage portability? It is a feature that may let you take your existing mortgage product to a new property, rather than paying an early repayment charge and starting again from scratch.
The word that catches people out is may. Lenders make portability sound simple, but it is never a guaranteed right to move your loan wherever you like. You will usually face a fresh affordability assessment, credit checks and a valuation of the property you want to buy. Treat it as a new mortgage application with one valuable potential benefit: keeping your current rate.
What Is Mortgage Portability in Practice?
A portable mortgage lets you transfer your existing mortgage deal when you move home, provided your lender agrees. Your old property is sold, the mortgage is repaid from the sale proceeds, and the lender creates a new mortgage secured against the new property. In plain English, you are not physically carrying the old loan from one house to another. You are asking the lender to honour the same product on a different home.
This is most useful when you are in the middle of a fixed-rate period. Leaving that deal early can trigger an early repayment charge, often called an ERC. Depending on your balance and the terms of the deal, that charge can run into thousands of pounds. Porting may allow you to avoid it.
But do not confuse avoiding an ERC with getting the best overall deal. The rate you are keeping may still be more expensive than another lender’s current product once fees, incentives and future flexibility are considered. The numbers need checking properly, not guessed at because the word “portable” sounds convenient.
Why Lenders Still Assess You Again
A lender agreed to lend against your current property and circumstances. It has not promised to lend against every future property you might choose. When you apply to port, it will usually look again at your income, committed spending, credit profile, deposit or equity, and the new property itself.
Your application can be declined if your earnings have dropped, you have taken on more borrowing, your credit record has changed, or the new property falls outside the lender’s criteria. Certain flats, ex-local authority properties, non-standard construction homes, properties above commercial premises and unusual rural properties can create problems with some lenders.
This is where home movers get a nasty surprise. They assume that because they have never missed a payment, portability is a formality. It is not. A clean payment record helps, but it does not replace the lender’s current affordability rules.
If you are self-employed, have recently changed jobs, receive variable income, are on maternity or paternity leave, or have a complex income structure, get the affordability position checked before you commit to a purchase. Do not wait until a seller has accepted your offer and the moving chain is underway.
The property has to pass too
The lender will value the new home and decide whether it is acceptable security. If it values the property below the purchase price, your loan-to-value calculation can change. You may need to put in more deposit, borrow less, or renegotiate the price.
The lender can also decline a property even where you can comfortably afford the payments. That is frustrating, but it is the reality of mortgage lending. The property, the borrower and the loan must all fit the criteria.
What Happens If You Need to Borrow More?
Most movers do. If you are upsizing, your portable balance may cover only part of the purchase. The lender might let you keep your existing deal on the old balance and take an additional loan for the extra borrowing.
That additional borrowing will normally be on one of the lender’s current products, often at a different interest rate and for a different fixed period. You could therefore end up with two mortgage parts, two rates and two deal end dates. This is sometimes called a split or blended mortgage arrangement.
It can work well, but it needs managing. When one part ends before the other, your options may be restricted or you may move onto the lender’s standard variable rate on one portion. Ask for the monthly payment now, the payment if rates rise after the fixed period, and the dates when each part can be changed without an ERC.
If you need a significant top-up, it may be worth comparing the porting route with remortgaging to a different lender and paying the ERC. That sounds counter-intuitive, but it can be cheaper over time. A good decision is based on the full cost, not on one fee viewed in isolation.
The Costs People Forget to Compare
Porting is not free simply because you retain your current rate. You may still pay valuation fees, legal fees, product fees for any extra borrowing, and the usual moving costs. Some lenders offer free valuations or legal work, but the detail matters.
You should also check whether a cashback deal or legal incentive from your original mortgage has a clawback condition. Some deals require you to repay an incentive if you leave or change the mortgage within a certain period. Porting may preserve it, but do not assume.
Timing can be another cost. Many lenders require the sale of your old home and the purchase of your new one to complete at the same time, or within a tight window. If your buyer pulls out and you have to break the chain, the lender’s rules can determine whether the ERC is refunded, waived, or charged for good.
Ask these questions before accepting an offer on a new property:
- Is my existing product definitely portable, and until what date?
- Will I pass today’s affordability checks based on my current income and spending?
- How much can I borrow on the new property, including any additional borrowing?
- What ERC applies if portability fails or the chain breaks?
- Will the extra borrowing sit on a separate rate and fixed period?
- Are there valuation, legal, product or incentive repayment costs?
Those answers turn a vague selling point into a decision you can rely on.
When Portability Can Make Sense
Porting often deserves serious consideration when you have a competitive fixed rate, a sizeable ERC, stable finances and a new property that should fit the lender’s criteria. It can reduce disruption and protect a deal that would be impossible to replace at current rates.
It may also be useful where your existing lender has already shown it can accommodate your circumstances. For example, someone moving locally from a starter home to a larger family house may prefer the certainty of retaining their existing mortgage rate, provided the top-up rate is reasonable.
That said, convenience is not a financial strategy. If another lender offers a better overall deal, greater borrowing flexibility, a longer term that reduces monthly pressure, or features that matter to you, such as overpayments, then portability may not be the winner.
When It Can Be the Wrong Move
Portability can become expensive or awkward if your existing lender has tight affordability rules, poor rates for additional borrowing, or limited flexibility around completion dates. It can also be a poor fit if you want to change the mortgage term substantially, move from repayment to interest-only, or alter the borrowers on the application.
A relationship change is a common example. If one person is being removed from the mortgage, the lender will reassess whether the remaining borrower can afford the debt alone. The fact that the mortgage is portable does not solve that affordability issue.
Buy-to-let borrowers should be equally careful. A residential mortgage product cannot simply be carried over to a rental property without the right permission or product. Lender criteria, rental coverage calculations and property type rules all matter.
How to Handle a Mortgage Move Without Guesswork
Start early – ideally before you put your home on the market or make an offer. Get your current lender’s porting terms, ERC figure and maximum additional borrowing in writing. Then compare that route with the cost of a fresh mortgage from the wider market.
Do not let an estate agent, lender call handler or well-meaning friend reduce the decision to “keep the low rate”. They are not looking at your whole position. You need to see the payment, fees, ERC, loan term, future rate risk and flexibility side by side.
A broker can test lender criteria before you become emotionally committed to a property, particularly if your income is complicated or you need extra borrowing. That is not paperwork for paperwork’s sake. It is how you avoid discovering a lender objection after you have paid for surveys, solicitors and searches.
Before you fall in love with the next house, get the porting numbers checked. Keeping a great rate can be smart. Paying thousands to preserve a deal that no longer suits your move is not.
