Moving with an existing mortgage comes down to one decision: take your current deal with you, which is called porting, or repay it and start a new one. Porting protects an interest rate that may be far better than anything available today and avoids an early repayment charge. Starting again gives you a cleaner structure and access to the whole market.
The thing most people get wrong is assuming porting is automatic. It is not. Most UK residential mortgages are portable in principle, but a port is a fresh application: the lender reassesses your affordability against today’s rules and has to accept the new property. A meaningful number of attempted ports are declined, and the reasons are usually predictable in advance.
Quick answer: Porting keeps your existing rate and avoids an early repayment charge, but requires passing a new affordability check and a valuation on the new property. Early repayment charges typically run 1 to 5 percent of the outstanding balance. If you are downsizing, expect a charge on the portion you do not carry across. Sale and purchase usually have to complete on the same day.
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The three routes compared
| Route | Keeps your rate? | Early repayment charge | Best for | Main tradeoff |
|---|---|---|---|---|
| Port the same amount | Yes | None, if done correctly | A good rate with time left to run | Fresh affordability check can fail |
| Port and borrow more | On the original portion only | None on the ported part | Trading up | A blended rate, and a second product with its own fee |
| Port less than you have | On the reduced amount | Yes, on the portion not carried across | Downsizing while keeping a good rate | The charge can outweigh the benefit |
| Repay and take a new deal | No | Yes, unless you are on SVR or the deal has ended | Rates have fallen, or your circumstances changed | Loses a favourable legacy rate |
| Let to buy | Separate arrangement | Depends on the product | Keeping the old property and letting it | More complex, consent to let or a buy to let product |
If your current deal has already ended and you are sitting on the standard variable rate, none of this applies in the same way. There is normally no early repayment charge on an SVR, so you are free to take whatever new deal suits without penalty.
Early repayment charges, and when they bite
An early repayment charge is typically 1 to 5 percent of the outstanding balance, and it applies to any part of the loan repaid ahead of schedule beyond your annual overpayment allowance. Most deals permit 10 percent a year without charge, which is why a partial port can still trigger a bill.
The arithmetic on downsizing is where this catches people. Suppose you owe £100,000 with a 10 percent annual overpayment allowance untouched, and the new property only needs an £85,000 mortgage. You are reducing the loan by £15,000. The first £10,000 falls within the allowance; the remaining £5,000 attracts a charge. At 3 percent that is £150, which is manageable. On a larger reduction it is not.
Run the comparison properly before deciding. A small ported mortgage on an old favourable rate is often worth less than people assume, because the saving is calculated on a smaller balance while the early repayment charge is calculated on the amount released. For substantial downsizes, taking a new deal frequently wins.
There is also a timing trap. Porting normally requires the sale and the purchase to complete on the same day. If there is a gap, some lenders treat the mortgage as redeemed and charge accordingly. Several will refund the charge if you take a new loan with them within a set window, commonly six months, on the same amount, rate and expiry date, but the conditions are strict and you have to pay first and reclaim.
Ask your lender for a redemption statement showing the exact charge before you commit to anything. The figure changes as the deal runs down, and a charge that looked prohibitive in January may be much smaller by September.
Why a port gets declined
Portability is a feature of the product, not a guarantee of approval. The lender re-runs affordability on current rules, re-values the new property against its lending criteria, and reviews your payment history. Any of the three can end it.
- Income has changed. A move to self-employment, a drop in bonus, or reduced hours can cut borrowing capacity even where the loan is not increasing.
- New debt. A car finance agreement or a larger credit card balance taken on since the original application reduces affordability.
- Credit history. Missed payments on the existing mortgage in particular can void portability outright.
- The property itself. Non-standard construction, flats above commercial premises, short leases and some new build types fall outside lending criteria regardless of your finances.
- Age. Many lenders cap the borrower age at the end of the term, which can bite on any new borrowing.
- A change of names on the mortgage. Adding or removing a person makes it a new application assessed from scratch.
Worth knowing: where you are not increasing your borrowing and have paid on time throughout, lenders have discretion to relax some affordability rules. They are permitted to do so rather than obliged, and the FCA has previously challenged several major lenders over ports refused on the basis of newer, tougher affordability tests. If you are declined in that situation, it is worth escalating rather than accepting it.
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Borrowing more, and the blended rate
Additional borrowing sits on a separate product at today’s rates, alongside the ported balance on the old rate. You end up with two sub-accounts and an effective blended rate, plus an arrangement fee on the new portion.
This is the structure most people trading up end up with, and it is worth understanding before you assume porting is the cheaper option. If you are porting £120,000 at a favourable legacy rate and adding £130,000 at current rates, the blended cost may be close to what a single new mortgage would charge across the whole balance.
The other complication is expiry dates. The ported portion keeps its original end date while the new borrowing has its own, so the two parts can come off their deals at different times. That means two remortgage decisions instead of one, and potentially an early repayment charge on one part if you want to move both together later.
Ask the lender to align the expiry dates if they will, or ask a broker to model both structures over the full term rather than comparing headline rates. This is exactly the situation where independent advice earns its fee, because the arithmetic is genuinely not obvious.
Costs on the port itself are usually modest. There is generally no arrangement fee on the ported portion, and a valuation on the new property that ranges from free to around £400 depending on the lender. Any additional borrowing brings its own arrangement fee.
Sequencing it against the purchase
We mapped the mortgage steps against the conveyancing timeline, because the two run in parallel and the mortgage is more often the thing that delays exchange than the legal work is.
| Stage | Mortgage action | Typical timing | What goes wrong |
|---|---|---|---|
| Before viewing | Redemption statement and decision in principle | A few days | People house-hunt without knowing their ERC |
| Offer accepted | Full application, port or new | Same week | Delay here delays everything downstream |
| Application submitted | Affordability assessment and documents | 1 to 3 weeks | Missing payslips and bank statements |
| Valuation | Lender values the new property | 1 to 2 weeks | Down-valuation reopens the whole deal |
| Mortgage offer issued | Formal offer to you and your solicitor | After valuation | Offers expire, commonly after 3 to 6 months |
| Exchange and completion | Funds drawn, sale and purchase same day | Set at exchange | A gap between the two can trigger an ERC |
Two findings are worth acting on. First, the redemption statement belongs at the very start, before viewings rather than after an offer. Knowing that your early repayment charge is £4,000 changes which properties you look at and whether you move at all this year, and it takes a phone call to find out.
Second, mortgage offers expire. If a chain drags past the offer validity, typically three to six months, the application has to be reassessed against your circumstances at that point rather than the original ones. Chains that stall for months are the most common reason a port that was approved in spring falls over in autumn.
This article is general information, not financial advice. Mortgage terms vary considerably between lenders and products, and a broker or your lender should confirm the position for your circumstances before you act. Your home may be repossessed if you do not keep up repayments on your mortgage.
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Keeping the old property instead of selling
Let to buy means keeping your current home, letting it out, and buying a new one to live in. It requires either consent to let from your existing lender or a switch to a buy to let product, and it changes both your tax position and your Stamp Duty liability.
Consent to let is the simpler route where a lender offers it, sometimes with a small fee or a rate adjustment, and it suits a temporary arrangement. Letting without consent is a breach of your mortgage terms and can put the lender in a position to demand repayment, so it is not a corner worth cutting.
The larger consideration is Stamp Duty. Buying an additional property while retaining the first attracts the higher rate on the new purchase, which on a mid-priced home is a substantial sum. There is a refund route if the original property is sold within a set window, but that requires actually selling it. Our guide to Stamp Duty when moving covers the surcharge position.
Deposit is the other constraint. Let to buy usually means releasing equity from the existing property to fund the deposit on the new one, which increases the borrowing on a property that now has to cover its own mortgage from rent. Lenders assess that rental coverage separately, and the numbers frequently do not work at higher loan to value.
This is firmly territory for a broker and an accountant rather than an article, because the tax treatment of rental income, mortgage interest relief and any eventual capital gain all interact.
When porting is the wrong choice
Do not port if current market rates are lower than your existing deal, if you are downsizing substantially, or if your circumstances have changed in a way that makes your current lender’s criteria a poor fit. Protecting a rate that is no longer good is a common and expensive mistake.
Porting is presented as the default sensible option almost everywhere, and for anyone holding a legacy rate well below the current market it usually is. The framing breaks down in three situations.
If rates have moved in your favour since you fixed, the whole rationale disappears. Compare the ported rate against what you could get today across the market rather than against the memory of what you were paying.
If your income structure has changed, particularly into self-employment or contracting, your existing lender may simply not be well suited to assessing you any more. A different lender with criteria that fit your circumstances can approve a larger loan than your current one will port, and being tied to the wrong lender is worse than losing a rate.
And if you are buying a property your lender will not accept, the decision is made for you. Establish the property type is acceptable early, because discovering it at valuation stage costs weeks.
How EcoGreen Movers fits around a mortgage timeline
Because porting usually requires sale and purchase to complete on the same day, the removals booking sits on a fixed date that cannot easily move. EcoGreen Movers quotes on a fixed basis and holds dates through the normal turbulence of a chain, which matters when the date is set by a lender rather than by you.
A same-day sale and purchase is a long day, and how long depends on what is left to do when the crew arrives. Premium means the packing is already finished, Standard Plus covers the furniture at both ends, and Standard covers the loading and unloading. Boxes are available on their own if you are packing during the mortgage application, which is otherwise waiting time. Storage matters here more than on most moves, because a same-day chain that slips leaves a household with a van and nowhere to unload.
We run residential moves across the UK, including London, Manchester and Edinburgh. For how the day itself runs, see our guide to completion day, or get in touch for a quote.
Frequently asked questions
Can I take my mortgage to a new house?
Usually, if the product is portable, which most UK residential mortgages are. It is not automatic though: the lender re-runs affordability against current rules, values the new property and reviews your payment history, and can decline on any of those grounds.
How much is an early repayment charge?
Typically 1 to 5 percent of the outstanding balance, often reducing as the deal approaches its end. It applies to any amount repaid early beyond your annual overpayment allowance, which is usually 10 percent. Ask for a redemption statement to get the exact figure.
Do I pay a charge if I am downsizing?
Often yes, on the portion of the loan you do not carry across, less any unused overpayment allowance. On a large reduction this can be substantial enough that taking a new deal on the smaller property works out cheaper overall.
Can I borrow more when I port?
Yes, subject to affordability. The extra sits on a separate product at current rates with its own arrangement fee, giving you two sub-accounts, a blended effective rate and potentially two different expiry dates to manage later.
What if my sale and purchase are not on the same day?
Porting normally requires simultaneous completion. Where there is a gap, some lenders treat the loan as redeemed and charge accordingly, then refund if you take a new loan with them within a set window, commonly six months, on matching terms. Confirm your lender’s position before agreeing dates.
In summary: get the redemption figure first
Call your lender for a redemption statement before you start viewing, so you know what leaving your deal would cost. Then compare the ported rate against the current market rather than assuming the old one wins, and model any additional borrowing as a blended cost rather than a headline rate.
Treat the port as a full application, because that is what it is. Get the documents together early, expect a valuation, and remember that a mortgage offer has an expiry date that a slow chain can outrun.
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