How private banks monetise cash and investments for mortgage affordability

by Aaron Strutt

Jul 29 2026

How private banks monetise assets for mortgage affordability? Is it possible to borrow against cash?

Private banks can sometimes use a wealthy borrower’s investment portfolio, savings, pensions, or other assets to support mortgage affordability, even if they no longer work or their regular salary is not high enough for a conventional lender.

They generally do this in several ways:

1. Lending against cash or investments to get a mortgage

The bank converts part of the client’s eligible assets into a theoretical annual income. For example, a client may have a £3 million investment portfolio but only draw a modest income. The bank might assume that an agreed percentage of the portfolio could be used each year to meet the mortgage payments.

A simplified calculation might be:

£3 million eligible portfolio × 4% = £120,000 annual notional income.

Or instant access cash in a savings account; some building societies can use 100% of this income over a five or ten-year term. So if £1 million in savings is divided over ten years, that equals £100,000 for affordability, and over a five-year term that increases to £200,000 as income.

The lender then applies income multiples of around five times and offers interest-only to lower the monthly costs. However, for stocks and shares, SIPPs or any variable income, some building societies use half of the value for affordability.   

The precise percentage, eligible assets and calculation period vary significantly between banks. The lender will normally apply a reduction or “haircut” to reflect investment risk and market volatility. 

Another large private bank, as a simple rule of thumb, would take £5 million and take off 20% - so £1 million - leaving £4 million. They would then divide the £4 million by the mortgage term, which is typically a maximum of 10 years, and this gives you the amount it would use for affordability in this case, £400,000.

The bank does not use income multipliers, but for the purpose of this example, working on the basis of 4.5X income would give a lending amount of £1.8 million.

Lenders may add investment income to a client’s salary, bonuses, pensions or rental income when assessing affordability.

Comment on lending against cash and investments from Trinity Financial's Aaron Strutt

“Many of the private banks are facing increased competition from the high street lenders to issue the more vanilla £1 million+ mortgages, which means they are being more creative to maintain their lending volumes. Lending against cash and investments is one of their niches.

"We are speaking to more high net worth clients who want to borrow against their investments and cash. One private bank recently agreed to lend a client £3.5 million against the £5 million cash he held over nine years on an interest-only basis.

"The lender also issued a £1.5 million mortgage based on the £6 million mixture of savings and investments over a ten-year term; he could have paid cash for the property but preferred to get a mortgage. In both cases the private bank did not ask for the assets to be transferred to them as part of the transaction.

“Another client, a UK resident, was looking to purchase a new home in London and required approximately £1.4 million to cover both the purchase price and associated stamp duty costs. Rather than liquidating investments, the client wanted to leverage an existing offshore investment portfolio valued at approximately $5 million, which was predominantly invested in the S&P 500. Maintaining his long-term investment portfolio was important to him, both to maintain market exposure and to avoid potential tax consequences associated with disposing of the assets.”

2. Investment income

Where a portfolio already produces dividends, interest or regular distributions, a private bank may use some or all of that income.

The bank is likely to review:

• The portfolio’s size and composition
• Historic income received
• Whether the income is sustainable
• The liquidity and volatility of the investments
• Whether the assets are held with the lending bank
• The country and curreney the assets are held in

Private banks often take a more comprehensive view of the borrower’s overall financial position than lenders relying mainly on salary multiples. 

3. Assets under management

Some private banks will offer more flexible mortgage terms when a client places investments or cash under the bank’s management.

The assets do not necessarily make the mortgage payments directly. Instead, they strengthen the overall banking relationship and give the lender greater visibility and control over the client’s wealth.

The bank may require a minimum amount to be transferred. Large private banks, for example, state that private banking accounts are available to clients with investment needs of £1.5 million or more, although individual lending requirements can differ.

4. Investment-backed or Lombard lending

Instead of selling investments, the client may borrow against an eligible portfolio. This is often called Lombard lending, securities-backed lending or investment-backed lending.

Coutts describes investment-backed lending as a way to release liquidity from a portfolio while keeping the underlying investments in place.

This can help provide:

• A larger property deposit
• Short-term funding pending a bonus or asset sale
• Money to reduce the required mortgage
• Liquidity without immediately selling investments

However, it is separate borrowing and normally carries its own interest costs. If investment values fall substantially, the bank may ask for additional security or repayment.

5. Using the overall balance sheet

Private banks may assess the client’s net worth, rather than looking only at their monthly income.

They may consider:

• Cash and investment portfolios
• Pensions
• Business ownership and retained profits
• Property equity and rental income
• Trust income
• Bonuses, carried interest and deferred remuneration
• Future liquidity events, such as a business sale

Coutts confirms that its mortgage approach can take account of complex remuneration and annual bonuses, while its guidance also refers to monetising assets such as investment portfolios.

Important distinction

Monetising assets does not simply mean that owning £2 million of investments automatically qualifies someone for a large mortgage.

The private bank will still need to demonstrate that the borrowing is affordable and sustainable. It will typically assess:

• The mortgage term and repayment strategy
• The client’s age and expenditure
• Whether the mortgage is repayment or interest-only
• The liquidity and diversification of the assets
• Potential investment falls
• Existing debts and financial commitments
• Tax implications and the client’s residency

Private banks are often most helpful for borrowers who are asset-rich but income-light, company owners retaining profits within a business, senior executives receiving irregular bonuses, investors with substantial portfolios, and clients seeking large interest-only mortgages.

Speak to a Trinity Financial adviser today

The mortgage market moves fast — and the right advice can make a significant difference to the rate and deal you secure. Get in touch with our team to discuss your options.

Call Trinity Financial on 020 7016 0790 to secure a fixed low deposit mortgage, book a consultation, or use our appointment calendar

The information contained within was correct at the time of publication but is subject to change. It is for general information purposes and is not advice.

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