Here’s how compounding is the key to Stocks and Shares ISA growth

Should we take out our Stocks and Shares ISA income each year, or reinvest it in more shares? The difference it makes could be huge.

| More on:

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.

Close-up of British bank notes

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.

What’s the best kind of ISA to go for, a risky Stocks and Shares ISA or a safe Cash ISA?

I don’t want a Cash ISA because the long-term returns are so poor. But they can be a boon for people who want the guaranteed safety they offer. Not everyone’s happy with stock market risk.

Whatever we go for, what difference would a few percent make anyway? Over just one year, maybe not a lot. But over the long term, it could add up to quite a bit. And it’s all down to the magic of compounding.

Compound returns

Hargreaves Lansdown senior investment analyst Joseph Hill tells us: “We asked people what they’d end up with if they invested £10,000 for a year, and their investments grew at 8%, compounded daily. Just 28% of people got the answer right. The most common answer was £10,800 – which is 8% growth without compounding.

What’s the correct answer? It’s £10,832, and the key is the bit about compounding daily. If the annual 8% is spread out with a tiny proportion paid every day, the first day’s income then earns its own return for the next 364 days. Then the next day’s income compounds for 363 days, and so on.

Now, £32 might not be a huge difference. But let’s try a real world example and see the difference that compounding can make over the long term.

Steady dividend stock

I’m going to pick British American Tobacco (LSE: BATS) as the example. It’s on a forecast dividend yield of 7.8%, and it has a long track record of steady payments. Suppose someone invests the same one-off £10,000, which is half an ISA allowance, into this stock and leaves it there for 10 years.

I’ll assume the share price and the dividend don’t change over the whole period. That’s unlikely, but it’s good enough for comparison purposes.

If they take out their dividend cash and keep it in a sack, they’d end up with an extra £780 per year. That would be a total of £7,800 after 10 years, the same as if it was paid all at the end, like in the Hargreaves Lansdown example. It’s 7.8% multiplied by the 10 years.

Years of compounding

But if, instead of just letting the dividends pile up, they reinvest the cash in more British American shares each year? Well, the pot could more than double to £21,000 from those compounded dividends alone. And £21,000 is a lot nicer than the £7,800 we’d expect if we didn’t reinvest the cash. It’s the difference that compounding can make.

I’ve no idea where the British American dividend or share price might go in the next 10 years. And I’d never put all my money into it. I’d be kept awake at night worrying about what might happen to the tobacco industry in the next decade. Diversification is essential.

But this snapshot example shows why we shouldn’t underestimate the power of compounding. And how the longer it goes on, the greater the difference it can make.

Alan Oscroft has no position in any of the shares mentioned. The Motley Fool UK has recommended British American Tobacco P.l.c. and Hargreaves Lansdown Plc. 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

Group of young friends toasting each other with beers in a pub
Investing Articles

FTSE 100 shares: has a once-a-decade chance to build wealth ended?

The FTSE 100 index has had a strong 2025. But that doesn't mean there might not still be some bargain…

Read more »

Passive income text with pin graph chart on business table
Investing Articles

I asked ChatGPT for its top passive income ideas for 2026 and it said…

Stephen Wright is looking for passive income ideas for 2026. But can asking artificial intelligence for insights offer anything valuable?

Read more »

Woman riding her old fashioned bicycle along the Beach Esplanade at Aberdeen, Scotland.
Investing Articles

Here’s how a 10-share SIPP could combine both growth and income opportunities!

Juggling the prospects of growth and dividend income within one SIPP can take some effort. Our writer shares his thoughts…

Read more »

Tabletop model of a bear sat on desk in front of monitors showing stock charts
Investing Articles

The stock market might crash in 2026. Here’s why I’m not worried

When Michael Burry forecasts a crash, the stock market takes notice. But do long-term investors actually need to worry about…

Read more »

Person holding magnifying glass over important document, reading the small print
Investing Articles

Is this FTSE 250 retailer set for a dramatic recovery in 2026?

FTSE 250 retailer WH Smith is moving on from the accounting issues that have weighed on it in 2025. But…

Read more »

Young Black woman using a debit card at an ATM to withdraw money
Investing Articles

I’m racing to buy dirt cheap income stocks before it’s too late

Income stocks are set to have a terrific year in 2026 with multiple tailwinds supporting dividend growth. Here's what Zaven…

Read more »

ISA Individual Savings Account
Investing Articles

Aiming for a £1k passive income? Here’s how much you’d need in an ISA

Mark Hartley does the maths to calculate how much an investor would need in an ISA when aiming for a…

Read more »

Two business people sitting at cafe working on new project using laptop. Young businesswoman taking notes and businessman working on laptop computer.
Investing Articles

Is investing £5,000 enough to earn a £1,000 second income?

Want to start earning a second income in the stock market? Zaven Boyrazian breaks down how investors can aim to…

Read more »