We have some exciting news to share! The Motley Fool UK has now become The Twelfth Magpie -- an independent, UK-owned company, led by our long-serving UK management team — Mark Rogers, Chris Nials and Heather Adlington. In practical terms, it’s the same team you know, now fully focused on serving our UK readers and members.

Just as importantly, our approach remains unchanged: long-term, jargon-free, and on your side. This site is our new home, and there will be extra tweaks made across the coming few days as we settle in. So if anything looks a little off, please bear with us!

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.

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.

You’re reading a free article with opinions that may differ from The Twelfth Magpie’s Premium Investing Services. Become a member today to get instant access to our top analyst recommendations, in-depth research, investing resources, and more. Learn more, and get a free 'Best Buy Now' stock!.

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.

Should you buy Rolls Royce shares today?

Before you decide, please take a moment to review this report first. Despite ongoing uncertainties from US tariffs to global conflicts, Mark Rogers and his team believe many UK shares still trade at substantial discounts, offering savvy investors plenty of potential opportunities to learn about.

That’s why this could be an ideal time to secure this valuable research – Mark’s analysts have scoured the markets to reveal 5 of his favourite long-term ‘Buys’. Please, don’t make any big decisions before seeing them.

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

Young brown woman delighted with what she sees on her screen
Investing Articles

Up 27.1% in 6 months: a FTSE 100 share paying out 2.8% a year!

This undervalued FTSE 100 share has suddenly soared in 2026. The stock still offers a decent cash yield, plus the…

Read more »

Investing Articles

Could now be the time to buy great UK shares at bargain prices?

Some UK shares have been trading exuberantly, with the FTSE 100 hitting hew highs in 2026. Does that mean there…

Read more »

piggy bank, searching with binoculars
Investing Articles

Prediction: this stock could surge 51% in my SIPP and ISA by 2027

Ben McPoland explains why he's bullish on this growth stock in his ISA and SIPP portfolios, despite it falling 25%…

Read more »

Satellite on planet background
Investing Articles

Is SpaceX on my list of shares to buy in July?

SpaceX shares have been falling. But the wait for a return from the business might be longer than the wait…

Read more »

ISA coins
Investing Articles

£10,000 put in a Cash ISA at the start of 2026 is now worth…

We're only halfway through the year, but has a Cash ISA beaten stock market returns so far? Our writer digs…

Read more »

Young woman carrying bottle of Energise Sport to the gym
Investing Articles

Still stubbornly in pennies, will the JD Sports share price hit £1 again?

Christopher Ruane reckons the JD Sports share price looks cheap but it's already been in pennies for many months. What's…

Read more »

Middle aged businesswoman using laptop while working from home
Investing Articles

Can an ISA outperform the stock market? Yes – here’s how!

Many investors dream of using their ISA to do better than the market overall. This writer knows it's possible --…

Read more »

Asian man looking concerned while studying paperwork at his desk in an office
Investing Articles

Dear SpaceX stock fans, mark your calendar for 7 July

SpaceX stock is getting fast-tracked into the world's leading technology index. Should I buy shares of the rocket maker before…

Read more »