UK mortgage guide · Last reviewed 25 July 2026

Remortgaging: compare the whole deal

Remortgaging usually means replacing the mortgage on your current home with one from a different lender. Moving to another deal with the existing lender is commonly called a product transfer. Either route can change the rate and payment, but the lowest advertised rate is not automatically the lowest-cost choice.

Why people review their mortgage

A fixed or discounted deal may move to a lender’s follow-on or standard variable rate when its initial period ends. Borrowers might also review a mortgage to change the term, alter repayment features, consolidate borrowing or release equity.

Changing the mortgage can create new costs and risks. Extra borrowing increases the debt secured against the home, and extending the term can reduce the monthly payment while increasing the time over which interest is charged.

Start before the current deal ends

Mortgage offers are often valid for a limited period, so it may be possible to arrange a new deal before the current one expires and schedule it to start afterwards. The available window and whether a rate can be changed before completion depend on the lender and offer.

Switching early can trigger an early repayment charge. Compare the cost of moving now with waiting until the charge ends, while recognising that a future mortgage rate cannot be known in advance.

Compare cost and balance over the same period

A fair comparison uses the same time horizon and includes payments, upfront costs and the mortgage balance remaining at the end. Looking only at the monthly payment can favour a longer term even though more debt remains. Looking only at the rate can overlook a large product fee.

Include product, booking, valuation, legal, advice and exit fees where they apply, along with cashback and any early repayment charge. If a fee is added to the mortgage, it also increases the balance on which interest may be charged.

Worked example

Consider a £360,000 repayment mortgage at 4% with 23 years remaining. Its modelled monthly payment is about £1,997. Switching immediately to 4.5% over the same term raises the modelled payment to about £2,096.

With a £1,499 switching cost and no cashback, the calculator estimates that switching costs about £10,189 more over five years after both payments and remaining balances are included. The example assumes both rates stay unchanged and illustrates why a new deal should be compared rather than presumed to be better.

Compare your figures with the Remortgage Comparison Calculator

Loan-to-value can affect available products

Loan-to-value, or LTV, compares the mortgage balance with the lender’s property valuation. Repaying capital or a higher valuation can reduce LTV, while a lower valuation can increase it. Different LTV bands can have different product rates and eligibility rules.

A lender’s valuation may not match an estate agent’s estimate or an online price. If additional borrowing is requested, use the total proposed secured borrowing when considering the future LTV.

Project equity and remortgage LTV

Product transfer or a different lender?

An existing lender may offer a product transfer with a simpler process, particularly when the balance, borrowers and mortgage terms are not changing. A different lender might offer a more suitable product but will generally apply its own valuation, eligibility, credit and affordability checks.

Convenience is part of the comparison, but it should not hide the total cost. Check what advice, legal work, valuation or administration is included and whether incentives have conditions.

Be careful with extra borrowing and debt consolidation

Adding unsecured debts to a mortgage can reduce the apparent monthly payment by spreading repayment over a longer period. It also converts the borrowing into debt secured against the home and can increase the total interest paid. Compare the full repayment cost and understand the consequences before proceeding.

Borrowing more can also change affordability, LTV and access to mortgage products. The Remortgage Comparison Calculator models the larger balance but does not decide whether additional borrowing is affordable or suitable.

Remortgage comparison checklist

Confirm the current balance, rate, remaining term and deal-expiry date.
Check the early repayment charge and mortgage exit fee.
Compare product fees, legal and valuation costs, advice fees and cashback.
Use the same term and time horizon before testing alternative terms.
Compare the remaining balance as well as monthly payments.
Check the lender’s valuation, LTV band, eligibility and affordability requirements.
Understand any overpayment limits, portability or other features you would lose or gain.

Related calculators

Independent information

This guide is educational information, not a mortgage recommendation or personalised financial advice. A lender or regulated mortgage adviser can assess actual products and eligibility.