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

3 ISA mistakes to avoid in 2025!

This trio of ISA mistakes can be costly. Our writer explains what they are and why he’ll try to avoid them next year — and 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.

ISA coins

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.

It is less than a month until the New Year. As an investor though, that means I still have around four months before my current ISA allowance expires. At that point, I will get another year’s allowance (unless the government monkeys about further, as it did with the proposed British ISA).

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.

With lots of potential to invest my ISA in 2025 and beyond, here are three mistakes I will be seeking to avoid.

Mistake 1: ignoring seemingly small costs

What is the difference between 1% and 1.5%? At face value, it may seem like there is little to chose. But an ISA is a long-term investment vehicle – and over the long term, seemingly small differences can add up.

For example, imagine £20k gets chipped away by 1% a year. After 20 years, it will be £16,358.

What if it gets chipped away by 1.5% each year for the same period? I will end up with £14,783. That strikes me as a big difference.

Before even considering how to invest my ISA then, I look at what options may be suitable for me and what charges each will impose.

There are lots of choices available so I want to make the choice that best suits my own financial circumstances and objectives.

Mistake 2: going ‘all in’ on one big idea

Still, even if the charges are higher, maybe I could still make bucketloads of cash if I choose the right shares?

Yes, I could. Putting a £20k ISA into Nvidia stock five years ago, for example, would mean I was now sitting on shares worth over half a million pounds (£547,000, in fact).

But such runaway successes are the exception not the rule – and even the best company can run into unforeseen difficulties.

So wise investors always spread their ISA over a range of shares.

Mistake 3: failing to spot a potential value trap

Another mistake is buying a share with an unusually high dividend yield, only to see it cut.

For example, Diversified Energy Company (LSE: DEC) and its 7% yield may look appealing. A few months ago though, that yield was actually quite a bit higher.

The company that specialises in buying up old gas wells has slashed its dividend. Not only that, the share price has tumbled 48% in five years.

That does not surprise me. High-yield shares that cut their dividend often see a share price fall as a result.

Diversified has some things going for it. It owns tens of thousands of wells. Thanks to its secondhand purchasing habits, it does not need to spend on exploration like many oil and gas majors do.

But it has borrowed heavily as it has grown, while facing risks from the cleanup costs of old wells to volatile energy prices.

I do not own this share partly because I fear such risks mean even the current dividend, though smaller than it was formerly, could be cut again.

If I had bought Diversified for my ISA before its dividend cut, I may now think I had fallen into a classic trap. That is one mistake I am always keen to avoid!

C Ruane has no position in any of the shares mentioned. The Motley Fool UK has recommended Nvidia. 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 »