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 £300 a month in a Stocks & Shares ISA to aim for a million

Who wants to be a Stocks and Shares ISA millionaire? I do! Here’s how I’d plan to reach this goal starting with a modest sum.

Young Black man sat in front of laptop while wearing headphones

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.

I use a Stocks and Shares ISA as my preferred way to invest for the future. Although it’s usually possible to buy many financial instruments within this tax wrapper, I tend to focus on owning its namesakes, stocks and shares.

With thousands of shares available, which ones work best for my goal? That’s what I’d like to answer today.

XXX

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.

Stocks and Shares ISA millionaire?

A £1m Stocks and Shares ISA might seem like an unreachable goal. And if I wanted to get there by next year, it certainly would be.

But the key to successful investing is to focus on the long term, in my opinion. Having a sufficiently long time horizon would allow my shares to grow.

The average stock market return is around 8%-10% per year. That’s across many decades of history. Bear in mind that past returns can’t guarantee what it will be in the future, but I use it as an estimate.

When I crunch the numbers, I calculate that if I invest £300 a month, I should reach my £1m goal within 35 years. It might sound like a very long time, but there are several strategies I could use to shorten it.

Speeding up the process

First, I could increase my monthly investment. Doubling it to £600 a month could enable me to reach my goal seven years earlier.

Alternatively, I could try to earn more than the average stock market return. Looking at the FTSE 350 index, I note that 14 shares achieved at least a 20% annual return over the past decade.

If I can match that, I’d expect to reach £1m within 22 years. That’s 13 years earlier than the original estimate.

Finding the best shares

When looking at the top performing shares over the past decade, there are several features that many have in common.

First, I note that many exhibit a high return on capital employed. This measure looks at how efficiently a company uses its money, or capital. I’d look for figures over 15% to find high-quality companies.

Next, the best performing shares aren’t typically the largest companies. A decade ago, many would have been small or medium-sized businesses.

That makes sense, as smaller companies can often grow faster. A popular investor, Jim Slater once coined the phrase, “elephants don’t gallop” to highlight this phenomenon.

However, smaller companies can be more volatile and could have wider swings in share price. But as I have a long time horizon, I should be able to withstand this volatility.

Top stocks

So which shares meet these criteria? With this year’s stock market weakness depressing share prices, there are currently several potential candidates.

For a new long-term Stocks and Shares ISA right now, I’d buy Softcat, Plus500, Games Workshop, Big Yellow Group, and IG Group.

On average, these five shares offer a return on capital employed of 50%. They also all produce a double-digit profit margin. That all sounds mighty appealing to me.

Harshil Patel has no position in any of the shares mentioned. The Motley Fool UK has recommended Games Workshop and Softcat. 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

Friends and sisters exploring the outdoors together in Cornwall. They are standing with their arms around each other at the coast.
Investing Articles

£503 buys 14 shares in this FTSE 250 stock that returned 23.9% annually for the last 15 years

This FTSE 250 stock has averaged a huge return for 15 years. At today's price, £503 buys 14 shares. But…

Read more »

Black woman using loudspeaker to be heard
Investing Articles

£1,000 buys 25 shares in this FTSE 100 stock that’s returned 29.2% annually for the last 10 years

This FTSE 100 mining stock has returned close to 30% a year for a decade. At 3,995p, £1,000 buys 25…

Read more »

Female student sitting at the steps and using laptop
Investing Articles

Down 47%, is this growth stock finally worth buying in May?

With a £288m order book and a hidden pipeline of defence and nuclear contracts, is this growth stock now too…

Read more »

House models and one with REIT - standing for real estate investment trust - written on it.
Investing Articles

2 REITs yielding 7%+ to consider for passive income in 2026

A REIT backed by the NHS and another backed by Tesco and Sainsbury's with both yielding 7%+. Here's why I'm…

Read more »

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

Just 97 shares of this UK dividend stock generate £238 in passive income

A 5.7% yield, £238 in passive income from just 97 shares, and one of the most divisive dividend stocks on…

Read more »

ISA coins
Investing Articles

£10,000 in an ISA generates a second income of…

The London Stock Exchange is home to some of the world's most generous dividends. But how big a second income…

Read more »

Shot of a senior man drinking coffee and looking thoughtfully out of a window
Investing Articles

Expert recommendations: 2 top income stocks yielding 7%+!

With yields of 7.2% and 7.8% respectively, these two income stocks are catching the eyes of institutional analysts. Should investors…

Read more »

Illustration of flames over a black background
Investing Articles

3 top income-focused stocks to buy in May 2026, according to experts

Looking for a stock to buy for income in May 2026? Experts have flagged these three UK dividend shares as…

Read more »