Islay Robinson examines the proposed bank tax increase ahead of the October Budget, exploring whether it could affect mortgage rates and why lender choice, mortgage offer validity and financing certainty matter for borrowers.

Reports ahead of the 28 October Budget suggest that Chancellor John Healey is considering increasing the tax surcharge on bank profits. One proposal reportedly under discussion would raise the surcharge from 3% to 8% on qualifying profits above £100 million, potentially raising an additional £2 billion to £2.25 billion annually. However, no change has been confirmed, and the final decision rests with the Chancellor.

The proposal would reverse the reduction introduced in April 2023, when the surcharge fell from 8% to 3% and the allowance increased to £100 million. With corporation tax at 25%, the combined rate on profits subject to the surcharge would rise from 28% to 33% if the reported proposal were adopted. The government's guidance on the bank surcharge explains the changes introduced in 2023.

I have no inside view on the Budget, and I would not treat a reported proposal as confirmed policy. What interests me is a more practical question: what should borrowers consider when the possibility of a policy change creates uncertainty around lending costs?

Could Higher Taxes on Banks Lead to Higher Mortgage Rates?

The argument from parts of the banking sector is that higher taxes could put pressure on lending economics, potentially affecting the price and availability of credit. The Trades Union Congress takes a different view, arguing that banks have benefited from higher interest rates and should make a greater contribution to public finances.

I can understand the reasoning on both sides. Banks need to remain profitable to lend, invest and compete, while the government must decide how to raise revenue and distribute the tax burden. Neither argument, however, establishes what mortgage rates will do next.

I would be cautious about assuming that a higher surcharge would translate directly into more expensive mortgages. Lenders have different funding costs, profit margins, customer bases and commercial priorities. Competition also matters. Some lenders may absorb additional costs, while others could reassess their pricing or lending appetite.

For borrowers, the practical implication is that lender choice becomes particularly important when the market is uncertain. Comparing options across high-street banks, specialist lenders and private banks may reveal meaningful differences in criteria, pricing and the way each lender assesses a particular application.

Why the Timing of a Mortgage Offer Matters

For a borrower considering a property purchase or refinancing, the timing of an application can be just as important as the rate being advertised. Mortgage pricing can change as lenders respond to funding costs, competition and market conditions. An advertised rate today is not necessarily the rate that will be available weeks later.

A formal mortgage offer can provide a degree of certainty because its terms generally remain available during the offer's validity period, subject to the lender's conditions. The duration varies by lender and product, so borrowers should check the expiry date and any circumstances that could affect the offer.

That distinction matters. Someone with a valid offer may have greater protection against a subsequent change in advertised rates than someone who has not yet secured one. However, an offer is not an unconditional guarantee that a transaction will complete. Changes to the borrower's circumstances, the property or the lender's requirements may still affect the outcome.

I would not recommend rushing into a mortgage simply because a Budget is approaching. The more useful step is to understand the available options, the expected transaction timetable and how long the proposed terms can be relied upon. Borrowers should also consider whether the mortgage remains appropriate for their circumstances if rates or other costs change later.

What This Means for Higher-Value Property Buyers

For buyers in the higher-value property market, arranging finance can involve more than comparing headline interest rates. The lender may need to assess complex income arrangements, assets held across different jurisdictions, the source of funds and the structure of the purchase. Those considerations can influence which lenders are suitable and how long underwriting takes.

A specialist lender's director has reportedly told Mortgage Introducer that uncertainty around the Budget and potential bank taxes was weighing on sentiment and property values. This is an industry perspective rather than proof that the speculation has caused prices to fall, but it reflects the cautious mood surrounding the market.

In my experience, the key question is not simply whether a rate might rise. It is whether the financing route is realistic for the borrower, whether the lender's criteria fit the transaction and whether the proposed terms are likely to remain suitable through to completion.

At Enness, we work with a network of more than 1,000 lenders, including private banks and specialist providers. Their criteria, pricing and appetite for different types of borrower can vary considerably. Exploring suitable options early can help borrowers understand the choices available, although it cannot guarantee approval, a particular rate or completion.

Three Dates Borrowers Should Keep in Mind

The Budget on 28 October is the immediate focus, but it is not the only event that could influence borrowing conditions. The next UK inflation release on 21 October and the Bank of England's interest rate decision on 5 November may also affect market expectations and lender pricing. The Bank of England's published Monetary Policy Committee dates provide details of scheduled rate decisions.

These events do not operate in isolation. Mortgage rates can respond to expectations about future interest rates, swap rates, funding costs and competition between lenders, rather than simply following the Bank of England's base rate. The effect of any Budget announcement will depend on the detail of the policy and how markets interpret it.

Until the Chancellor announces the final measures, I would avoid making financing decisions based on speculation alone. Buyers and homeowners should review their requirements, understand the validity of any existing offer and establish how much flexibility they have if their preferred terms change.

My main consideration is execution risk: the possibility that the financing available when a borrower starts planning is different from what is available when the transaction needs to complete. In a month containing a Budget, an inflation release and an interest rate decision, that possibility deserves attention.

The best response is preparation rather than panic. Understand the options, compare lenders where appropriate and make sure the proposed financing works for the transaction as a whole. The Budget may change the conversation around bank taxation, but until the details are confirmed, it is too early to conclude that mortgage rates will rise as a result.

Important Information

Your home may be repossessed if you do not keep up repayments on your mortgage or any other debt secured on it.

This article is for general information only and does not constitute personal financial or mortgage advice. Lending decisions, rates and terms are subject to individual circumstances and lender criteria. Mortgage rates and property prices can change, and property values can fall as well as rise. Enness does not provide tax, legal or investment advice. The bank tax proposal discussed in this article was unconfirmed as at 19 October 2026.

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