£20,000 Stocks and Shares ISA: how long would it take to reach £1 million?

This writer considers how long it would take an investor to reach a seven-figure sum by maxing out their Stocks and Shares ISA every year.

| 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.

Thoughtful man using his phone while riding on a train and looking through the window

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.

The Stocks and Shares ISA is a truly wonderful thing. Through one of these beauties, UK investors can build wealth without worrying about tax obligations.

Whatever returns are made are theirs to keep, with the contribution limit set at a generous £20k a year.

But how long could it realistically take to become an ISA millionaire? Let’s take a look.

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.

Powerful wealth-building vehicle

Boiling it down, the two key things are the amount contributed and the return on investment.

In other words, someone generating a 7% average annual return on a yearly investment of £5,000 is going to have to wait a lot longer than another achieving 10% on £20,000 invested every year.

For the former, it would take about four decades to reach £1m, whereas the person maxing out the full contribution limit each year would get there in just 19 years.

Indeed, the difference is so stark that the £20k-a-year ISA investor generating a 10% return would see the value of their portfolio rise above £8m after 40 years!

I should mention that these calculations assume that dividends are retained rather than spent. Ideally, they should be reinvested to fuel the compounding process.

I also haven’t factored in platform fees, which are a real cost that needs to be accounted for (they differ with each provider).

Still, the wealth-creating potential of the ISA is incredibly powerful for everyday investors. Reminding myself of this keeps me motivated to invest regularly.

Which stocks to buy?

There isn’t one single investing style to build wealth in the stock market.

Warren Buffett, for example, built an empire investing in businesses that he understood well. He looked for a margin of safety with the valuation, sticking to established and profitable companies with long track records.

As Buffett memorably put it, “It’s far better to buy a wonderful company at a fair price than a fair company at a wonderful price”. Buying an average company at a high price is a recipe for poor returns in the stock market.

Many other investors have made fortunes taking on more risk by investing in disruptive growth companies. Think Netflix as streaming started taking off 15 years ago, or Tesla in 2012 before electric vehicles went mainstream.

The Goldilocks zone

Arguably, the sweet spot is finding a wonderful company with strong growth prospects that is trading at an attractive valuation.

One potential example I see at the moment is Novo Nordisk (NYSE: NVO). This healthcare giant is a leader in diabetes and GLP-1 weight-loss treatments through brands like Ozempic and Wegovy.

The stock is down a whopping 54% since September!

The reason is that Novo Nordisk has fallen behind arch-rival Eli Lilly in the race to develop a GLP-1 pill (Wegovy is currently an injectable medication). So there’s a risk the company is losing its leading market position in this lucrative space.

Yet Novo Nordisk is still expected to grow strongly over the next few years, according to most analysts. And the global weight-loss market is projected to exceed $150bn in future — far too big to be dominated by any one company.

Meanwhile, the stock is trading at just under 14 times next year’s forecast earnings, and offering a 2.5% dividend yield. At $65, I really like the risk/reward setup and think it’s worth considering.

Ben McPoland has positions in Novo Nordisk. The Motley Fool UK has recommended Novo Nordisk and Tesla. 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 »