£1 Million+ Mortgages: Strategy for Rising Interest Rates

When mortgage rates are rising, the instinct is to try to time the market: fix before the next increase, wait for pricing to improve, or hope you have caught the bottom. On a large mortgage, I think that is the wrong approach.

Above £1 million, pricing is more individual, lender appetite can change quickly and small differences in rate can translate into significant sums. Having arranged mortgages from £1 million to well over £50 million for clients across approximately 80 nationalities, I have seen that the borrowers who achieve the strongest outcomes are rarely those who predict the market perfectly. They start early, secure a credible fallback and keep improving their position. For a large mortgage, rate strategy is a process, not a single decision.

Start six months out, not three

Six months is not about giving the application more time. It is about giving yourself more options. Private banks can change pricing, tighten loan-to-value limits, increase assets-under-management requirements or reduce appetite for particular borrowers and properties. The lender offering the best terms today may look very different three months from now.

Starting six months before your existing deal expires gives you time to test the market, secure a credible fallback and take advantage if a better option emerges. Leave it too late and the question shifts from what is the best structure available? to what can I get completed in time? At this end of the market, time is negotiating power. I would rather have six months to improve a client's position than six weeks to rescue it.

Your own bank first, but with your eyes open

Your existing lender should usually be the first call, but rarely the only one. A product transfer can be simpler and faster because the lender already knows you and the property. But with private banks, the mortgage rate can be part of a much wider relationship involving deposits, investments or assets under management. That matters because the easiest offer is not necessarily the cheapest overall proposition. A lower mortgage rate may look attractive, but not if securing it requires moving significant assets or accepting restrictions that outweigh the saving.

Get your existing lender's offer early and treat it as a benchmark, not the answer. Then test what the wider market will offer before deciding what that convenience is actually worth.

Test the market properly

There is no single market rate for a £1 million-plus mortgage. Private banks, specialist lenders, building societies and mainstream banks can look at the same borrower and arrive at very different terms. One may value assets under management, another may be more comfortable with complex or overseas income, while another has greater appetite for the property itself.

Pricing also moves with SONIA, swap rates, funding costs and lenders' appetite for new business. A lender that is uncompetitive today may look very different several weeks later. That is why one quote should never be mistaken for the market rate. Test the market widely enough to understand where your circumstances are most valuable. At this end of the market, securing the strongest terms is often less about finding the cheapest lender and more about finding the lender that most wants your particular deal.

Secure a worst-case position early

The first mortgage you secure does not have to be the one you ultimately complete on. Once you have identified a credible option, secure it as a fallback. If rates rise, you have a fallback, subject to the offer remaining valid and the lender's criteria continuing to be met. If pricing improves, you still have time to move. 

The key is preserving that flexibility without creating unnecessary sunk costs. Arrangement fees and valuations matter, particularly on high-value properties where repeated valuations can quickly erode any rate saving. I think of this less as choosing a mortgage and more as establishing a floor beneath the risk. You have a viable position if the market moves against you, without giving up the opportunity to improve it. In a rising market, certainty and flexibility can coexist.

Review every month

Securing a rate should not mean you stop watching the market. On a £5 million mortgage, even a modest improvement in pricing can materially change the interest bill. I would therefore review the market at least monthly until completion, comparing swap rates, lender pricing and appetite with the position already secured. I have seen lenders move from being uncompetitive to serious contenders during the same refinancing process as funding costs, pricing or appetite changed. The mistake is to think of the mortgage offer as the finish line. Until the loan completes, it is the position to beat.

The objective is not to secure the best rate available six months out. It is to arrive at completion with the strongest position available.

Do the maths on loan to value

A lower loan-to-value does not automatically mean a better financial decision. If reducing a £5 million mortgage by £500,000 moves you into a cheaper pricing band, calculate what that £500,000 actually saves in interest. Then compare it with what the capital could be doing elsewhere, taking into account liquidity, risk, tax and your wider financial objectives with the appropriate advisers.

For a high-net-worth borrower, that capital may otherwise sit in a business, investment portfolio or another property. Paying down debt has an opportunity cost, just as keeping the larger mortgage has an interest cost. The mortgage is one liability on a much larger balance sheet. Optimising it at the expense of everything else can be a very expensive way to save money.

Trackers are back in the conversation

A fixed rate is not automatically the conservative choice. Fixing gives certainty, but that certainty has a price. Compare the fixed rate with the margin on a tracker over Bank Rate and calculate how far rates would need to rise before the tracker became more expensive. On a multi-million-pound mortgage, that is more useful than guessing where rates will go next.

Early repayment charges matter too. A tracker with no, or limited, early repayment charge can preserve flexibility for someone expecting a property sale, bonus, business exit or other liquidity event. This does not make a tracker right for everyone. Tracker payments rise if Bank Rate rises, so you need to be comfortable with that exposure. The point is to ask what you are paying for certainty and what you give up getting it.

On a large loan, flexibility has a price. So does giving it up.

Think about the currency you borrow in

For an international borrower, the lowest mortgage rate is not necessarily the cheapest debt. If you borrow in sterling but earn or hold wealth in dollars, euros or dirhams, you are taking two positions: one on interest rates and another on currencies. On a multi-million-pound loan, exchange-rate movements can outweigh the benefit of a slightly lower mortgage rate.

The better question is not where can I get the cheapest rate? but which currency best matches the assets or income that will ultimately service or repay the debt? That exposure should be modelled rather than allowed to happen accidentally, with appropriate financial and tax advice. For an international borrower, currency is not a footnote to the mortgage. It is part of the price of the debt.

Use the whole balance sheet, not just the UK property

The property you want to refinance is not necessarily the property you should borrow against. An international client refinancing a London property may also own assets in France, Switzerland or elsewhere. Rather than automatically increasing borrowing against the UK property, it can be worth considering where capital could be raised most efficiently across the wider balance sheet.

That does not mean borrowing overseas because the headline rate is lower. Currency risk, local lending rules, tax, transaction costs and existing exposures all matter and require appropriate advice. Some overseas property finance is not regulated by the Financial Conduct Authority.  The important point is that a UK capital requirement does not automatically require a UK borrowing solution. For an international borrower, the better question is: where on the balance sheet does it make most sense for the debt to sit?

Check affordability holds

A secured rate is not the same thing as a secured mortgage. High-net-worth borrowers can have substantial assets but income that does not fit neatly into a lender's affordability model. Salary, bonuses, dividends, carried interest and investment income can all be treated differently.

That matters if circumstances change before completion. A different bonus, income structure or asset position can alter the affordability case on which the mortgage was agreed. Stress-test this at the outset. Understand which income the lender is relying on, what evidence it requires and whether that position is likely to change. For complex borrowers, the most attractive rate on paper is irrelevant if the structure cannot survive underwriting.

The rate is the output, not the strategy

The biggest mistake I see with large mortgages is treating the interest rate as the decision. It is not. The rate is the result of everything that comes before it. Nobody can reliably identify the perfect day to fix a mortgage six months in advance. What you can control is the process: starting early, creating options, protecting your downside and continuing to test the market until completion.

On a multi-million-pound mortgage, small differences matter. But the goal is not to save the final few basis points at any cost. It is to reach completion with the strongest appropriate financing position without unnecessarily compromising liquidity, flexibility or the wider balance sheet. You cannot control where interest rates go next. You can control how exposed you are when they get there.

 

Tracker and variable rates can rise as well as fall. Borrowing in a currency other than the one you earn or hold assets in exposes you to exchange-rate risk, which can increase the cost of repayments and the amount owed. Some overseas property finance is not regulated by the Financial Conduct Authority. Enness does not provide tax or legal advice; you should seek appropriate professional advice on your individual position.