12 February 2026

How to join the 5,000-strong ISA millionaires club

 

  • Someone investing the average annual Stocks and Shares ISA contribution would take around 41 years to reach a £1 million pot at a 5% annual return

 

Building a seven-figured ISA pot, commonly referred to as ISA millionaire, could take the average saver as long as 41 years, according to Rathbones, one of the UK’s leading wealth and asset management groups.

 

A Freedom of Information request submitted by Rathbones in January 2026* shows that the number of ISA millionaires has reached 5,070 (as of April 2023, the latest figure available), with 95% holding account values between £1 million and £2 million.

 

Rathbones’ calculations indicate that someone investing £7,594 a year – the average Stocks and Shares ISA contribution in the 2023/24 tax year – would need around 41 years to reach a £1 million ISA pot, assuming a 5% annual investment return before fees.

 

Angela Smith, Senior Investment Director at Rathbones, based in Glasgow, says: “The idea of becoming an ISA millionaire can feel like a distant dream reserved for high earners or lucky stock pickers. But the reality is far more encouraging. Many ISA millionaires didn’t sprint their way there — most started out with Personal Equity Plans (PEPs), long before ISAs existed. They built good habits, avoided common pitfalls, and let time and discipline do the heavy lifting.  

 

“From what we actively encourage with clients, the not‑so‑secret ingredient to building a large ISA — or any investment portfolio — isn’t perfect timing or extraordinary risk‑taking, but patience, time, and an iron‑clad discipline to keep investing and resist the temptation to tinker unnecessarily.”

 

There are several ways investors can improve their chances of reaching ISA millionaire status:

 

  • Risk and reward: At a higher 7% annual return - which may involve taking on more risk - the time needed to reach a real terms ISA pot worth today’s £1 million falls to around 34 years.
  • Increasing contributions: Raising the average annual contribution of £7,594 by 2% each year - for example, in line with pay rises - reduces the timeline by five years (to 36 years) at a 5% per annum return, and by ten years (to 31 years) at a 7% return.
  • Maximising the ISA allowance: Contributing the full £20,000 ISA allowance each year shortens the timeline by 17 years (to 25 years) at a 5% return, and by 22 years (to 20 years) at a 7% return.

 

Rebecca Williams, a Financial Planning Divisional Lead at Rathbones, based in London, says: “Becoming an ISA millionaire is impressive, but it doesn’t happen in a vacuum. A solid financial plan starts with the basics: having a cash buffer for emergencies and making sure your income and family are protected, so you’re not forced to dip into your ISA when things go wrong.

“It’s also worth remembering that ISAs don’t shelter wealth from inheritance tax. For those with very large ISA balances, failing to plan could mean a significant IHT bill down the line. That’s why pensions remain essential -they’re tax‑efficient, offer employer contributions, and for many people the value of that employer match can outweigh prioritising ISA saving alone.”

 

Tips for growing your ISA pot

 

Angela Smith says:

 

Start early and use pay rises as built‑in boosts

“Starting early gives your money more years to compound. Increasing your ISA contributions when your salary rises makes that compounding more powerful and ensures part of each pay rise is channelled into your future rather than absorbed by everyday spending.

 

Don’t interrupt compounding

“Compounding only works if you stay invested. Avoid knee‑jerk reactions to market volatility, as stop‑start investing breaks compounding’s momentum. Building an emergency fund of 3–6 months’ essential costs also reduces the risk of being forced to dip into your investments at the wrong time.”

 

Use as much of your ISA allowance as you realistically can

“ISA investments grow free from income tax and capital gains tax, and over decades this sheltering can be a major driver of long‑term returns. Using as much of your allowance as you can comfortably afford strengthens long‑term wealth building.”

 

Invest early in the tax year when you can

“Investing earlier in the tax year gives your money up to 12 extra months of potential compounding. You don’t need to use the full allowance at once — even smaller early contributions can make a meaningful difference.”

 

Choose investments that match your risk profile and goals

“Your portfolio should reflect your time horizon, risk tolerance, and long‑term objectives. Longer investment horizons often support higher equity exposure. Aim for a diversified mix of assets, regions, and sectors — rather than chasing short‑term performance.”

 

The ‘real terms’ ISA millionaire

Once you factor in inflation, £1 million in future pounds will not buy what £1 million buys today.

Angela Smith adds: “ISA millionaire status has enormous headline appeal — but the real question is what that money will buy in the future. With inflation steadily eroding purchasing power, the bar will only get higher. Disciplined behaviour matters more than ever. Standing still with your contributions effectively means slipping backwards in real terms.”