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

How to turn a £20k ISA into a £343 monthly second income

The key to turning cash today into a meaningful second income is compounding it at a high rate. Stephen Wright looks at the best way of doing this.

| 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.

Middle aged businesswoman using laptop while working from home

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.

With rising interest rates crushing the buy-to-let market, investors are looking elsewhere for a second income. And I think the stock market is a good place to look at the moment.

By investing using a Stocks and Shares ISA, I think £20,000 into an investment that can pay £4,116 per year – or £343 per month — is a sensible ambition. Here’s how.

The maths

A 5% compound annual return on £20,000 results in an investment that earns £4,116 per year after 30 years. I think that’s realistic, given the historic returns of the FTSE 100, but it’s a long time to wait.

Earning a higher average annual return could speed the process up, though. For example, earning a compounded return of 6% per year results in a portfolio generating £3,324 per year after 23 years.

With an 8% average annual return, the time to £343 per month halves compared to 5%. Compounded at 8% per year, £20,000 turns into an investment yielding £4,351 per month after 14 years.

Nothing is guaranteed when it comes to investing. But it’s worth noting that the difference between earning 5% and earning 8% can be quite significant when it comes to getting to £343 per month.

The strategy

Given this, I think it’s important to aim for the best overall return. And this involves looking for the most attractive opportunities across the board, rather than concentrating on growth or dividends. 

Obviously, the eventual ambition is a second income. But I don’t think that means I need to focus exclusively on shares in companies that distribute their earnings as dividends. 

There are two reasons for this. One is the best opportunities might not be in dividend stocks – and the cost of settling for a lower return in terms of time to get to £343 per year could be quite high.

Another is that I don’t need a business to distribute cash to earn a second income. If the companies I own shares in grow and retain earnings, I can always sell part of my stake to realise the increase. 

A stock to consider

In some ways, having an unlimited universe of stocks to choose from makes it harder. But one that I think looks attractive at the moment is Diageo (LSE:DGE).

Over the last decade, revenues have grown at around 4% per year and earnings per share at 5%. And this has happened while the company has returned most of its free cash to investors as dividends.

The growth isn’t risk-free, though. The company has recently proved that it isn’t as recession-resistant as some investors might have imagined as weak consumer spending has been weighing on demand. 

This has been an issue for companies across the board, though. And I think Diageo’s scale gives it an advantage over smaller rivals that should put it in a good position for the long term.

Opportunistic investing

Whether it’s growth or passive income, investing well comes down to seizing exceptional opportunities. That means buying shares in strong businesses when prices are unusually cheap.

Right now, I think Diageo fits the bill. That’s why I own the stock and why I plan to carry on buying it while the price stays near its current levels.

Stephen Wright has positions in Diageo Plc. The Motley Fool UK has recommended Diageo 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

Rolls-Royce's Pearl 10X engine series
Investing Articles

Can the Rolls-Royce share price do it again in 2026?

Can the Rolls-Royce share price do it again? The FTSE 100 company has been a star performer in recent years…

Read more »

Businessman hand flipping wooden block cube from 2024 to 2025 on coins
Investing Articles

After huge gains for S&P 500 tech stocks in 2025, here are 4 moves I’m making to protect my ISA and SIPP

Gains from S&P tech stocks have boosted Edward Sheldon’s retirement accounts this year. Here’s what he’s doing now to reduce…

Read more »

View of Lake District. English countryside with fields in the foreground and a lake and hills behind.
Investing Articles

With a 3.2% yield, has the FTSE 100 become a wasteland for passive income investors?

With dividend yields where they are at the moment, should passive income investors take a look at the bond market…

Read more »

Smart young brown businesswoman working from home on a laptop
Investing Articles

Should I add this dynamic FTSE 250 newcomer to my Stocks and Shares ISA?

At first sight, a UK bank that’s joining the FTSE 250 isn’t anything to get excited by. But beneath the…

Read more »

Investing Articles

£10,000 invested in BT shares 3 months ago is now worth

BT shares have been volatile lately and Harvey Jones is wondering whether now is a good time to buy the…

Read more »

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

After a 66% fall, this under-the-radar growth stock looks like brilliant value to me

Undervalued growth stocks can be outstanding investments. And Stephen Wright thinks he has one in a company analysts seem to…

Read more »

Content white businesswoman being congratulated by colleagues at her retirement party
Investing Articles

Don’t ‘save’ for retirement! Invest in dirt cheap UK shares to aim for a better lifestyle

Investing in high-quality and undervalued UK shares could deliver far better results when building wealth for retirement. Here's how.

Read more »

Black woman using smartphone at home, watching stock charts.
Investing Articles

1 growth and 1 income stock to kickstart a passive income stream

Diversification is key to achieving sustainable passive income. Mark Hartley details two broadly different stocks for beginners.

Read more »