Share your opinion and earn yourself a free Motley Fool premium report!

We are looking for Fools to join a 75 minute online independent market research forum on 15th / 16th December.

To find out more and express your interest please click here

£10k in an ISA? Here’s how I’d aim to turn it into £100k

With a regular savings plan, a sound investment strategy, and a long-term mindset, it’s possible to build up a huge ISA, says Edward Sheldon.

The content of this article was relevant at the time of publishing. Circumstances change continuously and caution should therefore be exercised when relying upon any content contained within this article.

Smiling young man sitting in cafe and checking messages, with his laptop in front of him.

Image source: Getty Images

You’re reading a free article with opinions that may differ from The Motley Fool’s Premium Investing Services. Become a Motley Fool member today to get instant access to our top analyst recommendations, in-depth research, investing resources, and more. Learn More.

ISAs (Individual Savings Accounts) are a great wealth-building tool. With these tax-efficient accounts, even a small amount of money can grow into a large sum, over time.

Here, I’m going to explain how I’d aim to turn £10k in an ISA into £100k. These are the moves I’d make to build up a six-figure account.

Please note that tax treatment depends on the individual circumstances of each client and may be subject to change in future. The content in this article is provided for information purposes only. It is not intended to be, neither does it constitute, any form of tax advice. Readers are responsible for carrying out their own due diligence and for obtaining professional advice before making any investment decisions.

The best way to build wealth

In my view, the best way to build up a large amount of capital within an ISA is to adopt a strategy that incorporates both saving and investing.

To state the obvious, saving is the process of putting some money away for the future. But investing, on the other hand, is the process of putting saved money to work in the hope of generating high long-term returns (above those on offer from savings accounts).

The secret to successful investing

Now, for the investing side of things, I’d put my money in the stock market (I’d need either a Stocks and Shares ISA or a Lifetime ISA to do this).

Over the long run, it has delivered returns of around 7-10% per year. That’s way higher than the returns generated by bonds and savings accounts.

However, to achieve these kinds of returns, one needs to build a decent investment portfolio.

History shows that not every stock is going to do well. So it’s important to diversify one’s capital over a range of different companies. That way, if a few shares underperform, one can still potentially generate solid long-term returns.

Building a top portfolio

The good news is that building a diversified stocks portfolio is very easy. Not only are there products like index funds that provide exposure to lots of different stocks for a low cost but there are also high-quality research services (like The Motley Fool) that can help investors build top-notch portfolios.

So I’d do my research – with the help of some experts – and set about building a diversified stocks portfolio that has exposure to a range of different companies.

I’d aim to invest in world-class businesses such as financial markets powerhouse London Stock Exchange Group, tech giant Alphabet (Google), Johnnie Walker and Tanqueray owner Diageo, and payments firm Mastercard.

All of these companies have amazing track records when it comes to generating wealth for investors over the long run.

Getting to £100k

How long would it take me to turn £10k into £100k using this strategy?

Well, it would depend on how much I saved every month and the level of return I was able to generate from my investments.

However, I calculate that if I saved £500 a month into a Stocks and Shares ISA and generated a return of 9% a year on my money over the long term, I could turn £10k into £100k in less than nine years.

Ed Sheldon has positions in Alphabet, Diageo Plc, London Stock Exchange Group Plc, and Mastercard. The Motley Fool UK has recommended Alphabet, Mastercard, and Diageo Plc. Suzanne Frey, an executive at Alphabet, is a member of The Motley Fool’s board of directors. Views expressed on the companies mentioned in this article are those of the writer and therefore may differ from the official recommendations we make in our subscription services such as Share Advisor, Hidden Winners and Pro. Here at The Motley Fool we believe that considering a diverse range of insights makes us better investors.

More on Investing Articles

Young woman holding up three fingers
Investing Articles

Want to start investing in 2026? 3 things to get ready now!

Before someone is ready to start investing in the stock market, our writer reckons it could well be worth them…

Read more »

Investing Articles

Can the stock market continue its strong performance into 2026?

Will the stock market power ahead next year -- or could its recent strong run come crashing down? Christopher Ruane…

Read more »

Businessman hand stacking money coins with virtual percentage icons
Investing Articles

Here’s how someone could invest £20k in an ISA to target a 7% dividend yield in 2026

Is 7% a realistic target dividend yield for a Stocks and Shares ISA? Christopher Ruane reckons that it could be.…

Read more »

A quiet morning and an empty Victoria Street in Edinburgh's historic Old Town.
Investing Articles

How little is £1k invested in Greggs shares in January worth now?

Just how much value have Greggs shares lost this year -- and why has our writer been putting his money…

Read more »

Businessman using pen drawing line for increasing arrow from 2024 to 2025
Investing Articles

This cheap FTSE 100 stock outperformed Barclays, IAG, and Games Workshop shares in 2025 but no one’s talking about it

This FTSE stock has delivered fantastic gains in 2025, outperforming a lot of more popular shares. Yet going into 2026,…

Read more »

Close-up of British bank notes
Investing Articles

100 Lloyds shares cost £55 in January. Here’s what they’re worth now!

How well have Lloyds shares done in 2025? Very well is the answer, as our writer explains. But they still…

Read more »

Thoughtful man using his phone while riding on a train and looking through the window
Investing Articles

How much do you need in an ISA to target £2,000 a month of passive income

Our writer explores a passive income strategy that involves the most boring FTSE 100 share. But when it comes to…

Read more »

Investing Articles

£5,000 invested in a FTSE 250 index tracker at the start of 2025 is now worth…

Despite underperforming the FTSE 100, the FTSE 250 has been the place to find some of the UK’s top growth…

Read more »