What should you do with short-term ISA cash?

Do you have cash in your ISA just waiting for a bargain? You could be damaging your returns.

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.

There’s the age-old question of whether it’s better to hold back some ISA cash for when you spot an unmissable bargain, or stay fully invested. I reckon most private investors would be better with the latter.

Over my investing career, the number of times I’ve thought “Wow, I must buy some of these shares, now” is very close to zero. Many times I’ve spotted something and thought it a compelling bargain, but my long-term success rate at spotting obvious grab-it-now shares runs at probably around 50%, which is no better than random!

At today’s ultra-low ISA interest rates, keeping cash in an ISA means you lose out on the returns you could be getting from shares. If you just bought National Grid shares, you’d earn around 5% per year in dividends, or there’s 6% on offer from BP.

You can still switch

Even if you do keep your ISA fully invested, that doesn’t mean you can’t dip into the odd bargain that comes up from time to time. If your ISA allowance is not fully used yet, you can just keep making monthly contributions to it until you have enough for a new purchase — and that gives you more time to fully investigate your short-term hunch.

My only recent example is Sirius Minerals, which I’d been keen on for some time. I finally bought some this month, at a slightly higher price than when I first started looking — but I see it as less risky now, and the time I waited and pondered was time well spent.

Even if you have no spare ISA capacity, you can still go for those occasional sure-fire bargains if you see them, by selling a portion of one of your other investments. That might sound like a diabolical idea to many, but dealing costs are actually very low these days, and if you do it only rarely it could be a good option.

If you have a big investment in, say, BP and you think some would be better in a hot new growth share, then moving the cash could be the right thing to do — selling when there’s a better opportunity is a key part of successful investing.

What to do with cash?

If you have ISA cash ready for a new investment, but there isn’t an obvious new share you want, what should you do? Especially if you’re keen on watching for any short-term opportunities?

I can only speak for myself, but I’d top up one of my existing holdings. I’d look for one paying solid dividends, and one with a narrow buy/sell spread to minimize any costs associated with switching to something new later — and that would pretty much tie me to FTSE 100 shares.

Of my current holdings, the one I’d top up would probably be Aviva, although I might go for Lloyds Banking Group. Both are paying decent dividends, and I think both are undervalued — though Lloyds is probably the more volatile of the two and the one less suited to a possible short-term switch. Other utilities, like SSE, or maybe even a depressed housebuilder like Taylor Wimpey, are among those I’d consider for a bit of spare ISA cash too.

And if you don’t spot that quick bargain, you’ll probably enjoy better returns from being fully invested.

Alan Oscroft owns shares of Aviva, Lloyds Banking Group, and Sirius Minerals. The Motley Fool UK has recommended BP. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors.

More on Investing Articles

Asian man looking concerned while studying paperwork at his desk in an office
Investing Articles

A stock market crash feels like it might be imminent

Conflict in the Middle East means a stock market crash feels like a real possibility right now. But being ready…

Read more »

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

Should I buy Rolls-Royce shares as they march ever higher?

Rolls-Royce is making billions of pounds a year and looks set to do even better in future -- so what's…

Read more »

Smiling family of four enjoying breakfast at sunrise while camping
Investing Articles

£1,000 buys 110 shares in this UK beverage stock that’s smashing Diageo 

Shares of Tanqueray-maker Diageo are languishing at multi-year lows. So why is the stock behind this tonic water brand on…

Read more »

UK financial background: share prices and stock graph overlaid on an image of the Union Jack
Investing Articles

What next for Aviva shares after a cracking set of 2025 results?

Aviva achieving its 2026 financial goals a year ahead of schedule has got to be good for the shares... oh,…

Read more »

This way, That way, The other way - pointing in different directions
Investing Articles

Should I buy stocks or look to conserve cash right now?

In a market dealing with AI uncertainty and conflict in the Middle East, should investors be looking for stocks to…

Read more »

Investing Articles

Here’s how many British American Tobacco shares it takes to earn a £1,000 monthly second income

Is an AI-resistant business with a 5.38% dividend yield a good choice for investors looking for a second income in…

Read more »

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

1,001 Barclays shares bought 12 months ago are now worth…

Barclays shares have delivered excellent returns over the last year. But can the FTSE 100 bank keep outperforming? Royston Wild…

Read more »

Two business people sitting at cafe working on new project using laptop. Young businesswoman taking notes and businessman working on laptop computer.
Investing Articles

Get started on the stock market: 3 ‘safe’ shares for beginner UK investors to consider

Kicking off an investment portfolio on the stock market may seem like a scary prospect. Mark Hartley details a few…

Read more »