How I’d invest a £20,000 Stocks and Shares ISA to help build long-term wealth

Our writer shares his approach to compounding income in his Stocks and Shares ISA with the objective of growing wealthier over time.

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.

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.

People use their ISAs in different ways. Sometimes, a Stocks and Shares ISA can be a helpful way to produce passive income streams for the coming months and years.

But an alternative is to use a Stocks and Shares ISA to try and build some long-term wealth. Here is how I would go about that.

Growth or income focus?

One way to build wealth for the long term is to find companies in their early stages that may have a great future ahead of them. If I can invest £20,000 today in shares that increase a hundred-fold over the next couple of decades, I would end up with a couple of million pounds for my efforts!

The difficulty with that approach is that, for every share that becomes a hundred-bagger, there are loads that do not even keep their value in the long term, let alone increase it dramatically. Even the most successful stock pickers often have a portfolio containing quite a few duds, alongside the star performers.

That is why I think a more realistic approach to building my long-term wealth could be to buy high income shares and continually reinvest the dividends.

The power of compounding

Why would I reinvest the dividends in my Stocks and Shares ISA? The reason is I want to benefit from what is known as compounding.

Warren Buffett illustrates compounding with a snowball. As the snowball goes downhill, it picks up more snow. Crucially, the snow it picks up then picks up more snow. That means that over time, it gets bigger and bigger as the growth itself produces growth.

If I reinvest dividends, I could try to get the same benefit. Imagine I invest £20,000 in shares with an average yield of 5% like Aviva and reinvest the dividends annually. Presuming the share price and dividends stay flat, after 25 years, my ISA would be worth over £69,000.

If I invested in shares yielding an average 7% like Legal & General, after 25 years my ISA value would be over £114,000. Even more dramatic is what happens if I invest in shares with an average yield of 10% like Persimmon. After 25 years, the £20,000 I put in my ISA today would have grown to £241,000.

Managing risk in my Stocks and Shares ISA

However, what happens if things change? After all, 25 years is quite a long time. Companies may cut or cancel their dividends. A quarter of a century from now, they may even have gone out of business altogether.

I try to mitigate that risk by spreading my Stocks and Shares ISA across a number of companies. I also am not buying shares purely for their yield. Instead, I ask myself what their long-term business prospects are like. Do I think they have the ability to make strong profits to fund their dividend payments years into the future?

By investing in carefully chosen income shares, I hope my Stocks and Shares ISA can help me grow my wealth in the coming decades.

Christopher Ruane has no position in any of the shares mentioned. The Motley Fool UK has no position in any of the shares mentioned. 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

Yellow number one sitting on blue background
Investing Articles

I asked ChatGPT to pick 1 growth stock to put 100% of my money into, and it chose…

Betting everything on a single growth stock carries massive danger, but in this thought experiment, ChatGPT endorsed a FTSE 250…

Read more »

Portrait of pensive bearded senior looking on screen of laptop sitting at table with coffee cup.
Investing Articles

How little is £1,000 invested in Diageo shares at the start of 2025 worth now?

Paul Summers takes a closer look at just how bad 2025 has been for holders of Diageo's shares. Will things…

Read more »

Aston Martin DBX - rear pic of trunk
Investing Articles

After a terrible 2025, can the Aston Martin share price bounce back?

The Aston Martin share price has shed 41% of its value in 2025. Could the coming year offer any glimmer…

Read more »

Close-up of British bank notes
Investing Articles

How much do you need in an ISA to target £3,000 per month in passive income?

Ever thought of using an ISA to try and build monthly passive income streams in four figures? Christopher Ruane explains…

Read more »

piggy bank, searching with binoculars
Investing Articles

Want to aim for a million with a spare £500 per month? Here’s how!

Have you ever wondered whether it is possible for a stock market novice to aim for a million? Our writer…

Read more »

Investing Articles

Want to start buying shares next week with £200 or £300? Here’s how!

Ever thought of becoming a stock market investor? Christopher Ruane explains how someone could start buying shares even on a…

Read more »

Rear view image depicting a senior man in his 70s sitting on a bench leading down to the iconic Seven Sisters cliffs on the coastline of East Sussex, UK. The man is wearing casual clothing - blue denim jeans, a red checked shirt, navy blue gilet. The man is having a rest from hiking and his hiking pole is leaning up against the bench.
Investing Articles

2 ideas for a SIPP or ISA in 2026

Looking for stocks for an ISA or SIPP portfolio? Our writer thinks a FTSE 100 defence giant and fallen pharma…

Read more »

Midnight is celebrated along the River Thames in London with a spectacular and colourful firework display.
Investing Articles

Could buying this stock at $13 be like investing in Tesla in 2011?

Tesla stock went on to make early investors a literal fortune. Our writer sees some interesting similarities with this eVTOL…

Read more »