Isa investing: tips to become an ISA millionaire

There are more than 4,000 investors who have become ISA millionaires. Fancy joining the club? Here's what you need to do.

ISAs are not just cracking vehicles for shielding your funds from the taxman ‒ they could turn you into a millionaire.

In fact, there are more than 4,000 investors who can legitimately call themselves ISA millionaires.

Remarkably, figures from HMRC, revealed following a freedom of information (FOI) request by Openwork Partnership a few months back, found that the 50 most successful ISA investors had amassed pots worth a staggering £8.5 million on average.

The average pot size among all ISA millionaires was a none-too-shabby £1.4 million.

Fancy joining the club? Let's take a look at what you need to do.

Want to be an ISA millionaire? Get active

Analysis by investment firm AJ Bell found that of the 472 funds and trusts which stretch back to 1999, when ISAs were first launched, only 50 would have helped savers grow their balance to seven figures.

What’s more, of course, that relies on having invested the full ISA allowance each and every year.

It’s also notable that every one of these funds and trusts is actively managed, meaning there is a fund manager determining where to invest.

AJ Bell noted that passive funds, which track the performance of an investment index like the FTSE 100, were not as prevalent back in 1999, while they also don’t generally cover the smaller companies sector.

This is important since this sector has been a big part of the funds and trusts that have helped create ISA millionaires.

Investment trusts and funds that have made millionaires

So which investments could have helped turn you into an ISA millionaire?

We'll start with some new analysis by the Association of Investment Companies (AIC), which has identified 32 investment trusts that would have surpassed £1 million by today.

Its calculations assume investors made use of their full ISA allowance every year between 1999 and 2023 – meaning total deposits of £306,560 – and reinvested the dividends.

You can see the full list below but, as AIC points out, "technology is a strong theme among the top four trusts" while more than a third (12) are focused on smaller companies.

The 32 “ISA millionaire” investment trusts 1999-2023

There is also data on the best-performing funds, although admittedly this is a little older, having been compiled in March 2023.

This was put together by AJ Bell and, again these look at performance since 1999 and assume you maximised your ISA allowance each year.

10 best-performing funds

That they have still produced sufficient returns since 1999 to have turned savers into millionaires is a good demonstration of why it’s crucial to take a long-term view with investing, since there will inevitably be peaks and troughs.

How can you become an ISA millionaire?

Simply knowing the names of these top-performing funds and trusts will not necessarily help you follow in the footsteps of ISA millionaires.

Instead, you need to take lessons from the savers who have managed to build such big balances, and see which you can apply to your own habits to join the ISA millionaire club.

It’s important to emphasise that simply setting aside the maximum each year is not going to be sufficient.

As Laura Suter, head of personal finance at AJ Bell, pointed out last year, if you put the full allowance in an ISA each year between 1999 and 2022 and earned a 5% return, you’d be sitting on around £441,000, some way off hitting seven figures.

Instead, you need patience ‒ and a little bit of luck along the way.

So with the ISA deadline on the horizon ‒ remember you have until midnight on 5 April to use this year’s £20,000 ISA allowance ‒ here’s our guide to the steps you can take to (potentially) join the ranks of the ISA millionaires.

1. Get cracking

The only way you can start on the path to becoming an ISA millionaire is by getting some money – no matter how small – into an ISA.

You don’t need to start with a big cash sum, small regular savings will soon start to build up. As little as £85 a month would give you over £1,000 in 12 months.

If you do start small, make a note in your diary to re-assess how much you are saving once a year to see if you can afford to tuck a little more away.

2. Make the most of your allowances

Allowances have rocketed in recent years, with the annual ISA allowance now standing at £20,000, up from £7,000 a decade ago.

But no one knows what the future holds, and allowances could fall.

Read more: How to transfer an ISA

3. Reinvest your dividends

It can be tempting to take any dividends your ISA earns as an income but reinvesting them into your portfolio will have a significant effect on your overall returns as you are compounding the growth.

4. Take some risks

The stock market can be a scary place, but don’t stunt your capital growth by being too risk-averse.

If you are putting money aside for the long-term – think 10 years or more – then it’s generally accepted that your money has a better chance of growing substantially if it is invested in the stock markets rather than in a Cash ISA.

5. Travel the world

Diversification is the key to building a successful investment portfolio. That doesn’t just mean investing in different asset classes it also means exposing your portfolio to numerous markets around the world.

Emerging markets may be riskier than investments in more developed countries, but they are also economies with more potential for faster growth.

6. Don’t go mad

While a little bit of risk may help your portfolio grow, don’t stick all your money in high-risk investments.

You need to be comfortable with the risk, and the potential loss it could result in.

Make sure your whole portfolio reflects your overall attitude to risk.

That could mean spreading your investments across a variety of risk levels.

7. Use an expert

While there are some ISA millionaires who have built their fortunes through investing in individual stocks, most people prefer to use the expertise of a fund manager.

“While tracker funds are an excellent way to get started with the stock market, many of these more experienced investors, with much larger portfolios, have selected a recommended manager who runs a relatively concentrated portfolio,” according to Hargreaves Lansdown.

“That way they have the potential to amplify growth, without necessarily having to become an expert in those stocks themselves.”

8. Don’t chop and change too much

Investing is a long-term process and you need to take a long view.

You should certainly keep an eye on your portfolio to make sure its performance is meeting your expectations but don’t constantly trade investments.

Buying and selling constantly will dent your overall growth due to higher transaction costs and you could also miss out on the long-term growth story of a fund or share.

9. Ride out the bad times

The stock market can be a turbulent place but building a large, successful portfolio is all about holding your nerve when the markets are tough.

Don’t try to time the market – the chances are you’ll get it wrong.

The major investment mistake too many people are making

10. Get the family on board

You might have your own ISAs in hand, but what about the rest of your family?

Try to get your spouse or partner to make the most of their ISA allowance too and don’t forget that you can tuck money into Junior ISAs for your children.