Cash ISA versus the FTSE 100: Which should you choose?

Rupert Hargreaves explains why he thinks investing in the FTSE 100 (LON:INDEXFTSE: UKX) is always worth the risk.

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.

When it comes to saving for the future, tens of thousands of savers open a Cash ISA every year. While there’s nothing wrong with opening a Cash ISA, even the best interest rates available on the market today don’t compensate savers for the risks they are taking by leaving their money in cash.

The biggest risk savers face

The biggest risk cash savers face is inflation. Inflation can make cash savings, which many savers believe are risk-free, exceptionally risky. Every year, inflation chips away at your wealth. And if you are not earning a rate of interest that’s greater than the rate of inflation, then your money is actually losing value.

According to my research, the best Cash ISA interest rate available on the market today is around 1.5% for an easy access product, or 2.3% if you are willing to lock your money away for five years.

By comparison, the annual inflation rate for the UK during the first quarter of 2019 averaged 1.9%, which implies money in a flexible Cash ISA receiving an interest rate of 1.5% will lose 0.4% of its purchasing power this year.

In my opinion, inflation risk is the primary reason why the FTSE 100 is currently a better investment than Cash ISAs.

Inflation protection

With a dividend yield of 4.4% at the time of writing, the FTSE 100 more than compensates investors for the risk of inflation. On top of this, company earnings tend to increase with inflation over the long term as businesses increase their prices. This means the capital value of the FTSE 100 should increase with inflation over time as well.

So that’s inflation dealt with. But what about the risk volatility? While it’s true the FTSE 100 does go up and down on a day-to-day basis, over the long term, the index has only gone up.

Between 1999 and the end of 2018, the FTSE 100 produced a total return of 93.5%, which I think is an awe-inspiring return considering the fact that this two-decade time frame contains not one but two severe bear markets, the bursting of the dot.com bubble and the financial crisis.

The very fact that the FTSE 100 almost doubled investors money during this time frame, which was one of the most turbulent periods for financial markets for some time, stands testament to its ability to create wealth over the long term.

The bottom line

There’s nothing wrong with putting a portion of your savings in a Cash ISA but, as I’ve explained above, even though the tax advantages of this product are attractive, the current interest rates available don’t make up for the risk of inflation.

With that in mind, I think the FTSE 100 is a much better place to invest your money today. What’s more, owning a FTSE 100 tracker fund inside a Stocks and Shares ISA will achieve the same tax benefits and a much better return on your money over the long term.

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

British bank notes and coins
Investing Articles

Here’s a £30-a-week plan to generate passive income!

Putting a passive income plan into action need not take a large amount of resources. Christopher Ruane explains how it…

Read more »

Close-up of British bank notes
Investing Articles

Want a second income? Here’s how a spare £3k today could earn £3k annually in years to come!

How big can a second income built around a portfolio of dividend shares potentially be? Christopher Ruane explains some of…

Read more »

Close-up of British bank notes
Investing Articles

£20,000 for a Stocks and Shares ISA? Here’s how to try and turn it into a monthly passive income of £493

Hundreds of pounds in passive income a month from a £20k Stocks and Shares ISA? Here's how that might work…

Read more »

Snowing on Jubilee Gardens in London at dusk
Investing Articles

£5,000 put into Nvidia stock last Christmas is already worth this much!

A year ago, Nvidia stock was already riding high -- but it's gained value since. Our writer explores why and…

Read more »

Investing Articles

Are Tesco shares easy money heading into 2026?

The supermarket industry is known for low margins and intense competition. But analysts are bullish on Tesco shares – and…

Read more »

Smiling black woman showing e-ticket on smartphone to white male attendant at airport
Investing Articles

Can this airline stock beat the FTSE 100 again in 2026?

After outperforming the FTSE 100 in 2025, International Consolidated Airlines Group has a promising plan to make its business more…

Read more »

Investing Articles

1 Stocks and Shares ISA mistake that will make me a better investor in 2026

All investors make mistakes. The best ones learn from them. That’s Stephen Wright’s plan to maximise returns from his Stocks…

Read more »

Portrait Of Senior Couple Climbing Hill On Hike Through Countryside In Lake District UK Together
Investing Articles

I asked ChatGPT if £20,000 would work harder in an ISA or SIPP in 2026 and it said…

Investors have two tax-efficient ways to build wealth, either in a Stocks and Shares ISA or SIPP. Harvey Jones asked…

Read more »