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

ISA vs SIPP: which could make you a millionaire first?

ISAs and SIPPs can both help you build your financial nest egg, but which one is better if you want to make a million in the shortest time?

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.

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.

ISAs and SIPPs are both great products to help save for the future. However, while these products do have some similarities, they are very different. 

For example, investors can only contribute a maximum of £20,000 into an ISA every year. Meanwhile, SIPP contributions are effectively capped at £40,000 a year as any contributions above that level attract tax penalties. 

SIPP contributions also attract tax relief at your marginal tax rate. That’s 20% for basic rate taxpayers. So, for every £80 contributed, the government will add an extra £20 to take the total to £100. These additional contributions may decrease the time it takes to make a million.

That said, while you can put more money away every year using a SIPP, the product has some drawbacks, which means it might not be suitable for all investors. 

ISA benefits 

The biggest drawback of using a SIPP is the fact that money cannot be withdrawn until the owner is 55 years of age. What’s more, you can only take out a 25% tax-free lump sum. Any money withdrawn after that is taxed at your marginal tax rate. 

On the other hand, money put into an ISA does not warrant any special tax treatment. You can take the money out whenever you want, and don’t have to worry about incurring any additional tax liabilities. So-called flexible ISAs also allow you to take out and put in as much money as you want every year as long as you do not breach the £20,000 limit. 

As such, if you want total control over your money, an ISA may be the best product to use to make a million. However, the tax benefits that come with a SIPP suggest that it will make you a millionaire first. 

Investing for wealth 

The best way to invest your money in one of these tax-efficient wrappers could be to use a FTSE 100 tracker fund. Over the past three-and-a-half decades, the FTSE 100 has produced an average annual return in the region of 7%. At this rate of return and paying in the maximum amount, it would take just 15 years to build a £1m nest egg using a SIPP, according to my calculations. To reiterate, that’s assuming an average annual contribution of £40,000, although that wouldn’t be possible for many savers. 

With contributions limited to just £20,000 a year, it would take 22 years to reach the same target in an ISA from a standing start. 

It may be possible to reach this target even faster using individual shares. Now could be the perfect time to buy a diverse portfolio of undervalued FTSE 100 stocks after the recent stock market crash. Many blue-chip companies are trading at depressed levels, which reflects the uncertainty hanging over the global economy.

Clearly, these companies are unlikely to generate substantial returns in the near term, but over the long run, the market should recover from its recent setback.

As investor sentiment improves, that could mean significant returns for investors buying today with a long-term outlook. If these stocks are owned in an ISA or SIPP, there will be no capital gains tax to pay when it is time to sell. 

Rupert Hargreaves owns no share 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 woman holding up three fingers
Investing Articles

Want to start investing in 2026? 3 things to get ready now!

Before someone is ready to start investing in the stock market, our writer reckons it could well be worth them…

Read more »

Investing Articles

Can the stock market continue its strong performance into 2026?

Will the stock market power ahead next year -- or could its recent strong run come crashing down? Christopher Ruane…

Read more »

Businessman hand stacking money coins with virtual percentage icons
Investing Articles

Here’s how someone could invest £20k in an ISA to target a 7% dividend yield in 2026

Is 7% a realistic target dividend yield for a Stocks and Shares ISA? Christopher Ruane reckons that it could be.…

Read more »

A quiet morning and an empty Victoria Street in Edinburgh's historic Old Town.
Investing Articles

How little is £1k invested in Greggs shares in January worth now?

Just how much value have Greggs shares lost this year -- and why has our writer been putting his money…

Read more »

Businessman using pen drawing line for increasing arrow from 2024 to 2025
Investing Articles

This cheap FTSE 100 stock outperformed Barclays, IAG, and Games Workshop shares in 2025 but no one’s talking about it

This FTSE stock has delivered fantastic gains in 2025, outperforming a lot of more popular shares. Yet going into 2026,…

Read more »

Close-up of British bank notes
Investing Articles

100 Lloyds shares cost £55 in January. Here’s what they’re worth now!

How well have Lloyds shares done in 2025? Very well is the answer, as our writer explains. But they still…

Read more »

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

How much do you need in an ISA to target £2,000 a month of passive income

Our writer explores a passive income strategy that involves the most boring FTSE 100 share. But when it comes to…

Read more »

Investing Articles

£5,000 invested in a FTSE 250 index tracker at the start of 2025 is now worth…

Despite underperforming the FTSE 100, the FTSE 250 has been the place to find some of the UK’s top growth…

Read more »