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Every spring, something predictable happens across the country. As the 5 April tax-year deadline approaches, many people rush to pay into their ISA before the window closes. The scale is striking: in April 2025 alone, savers paid around £14 billion into ISAs – the highest monthly figure since ISAs began in 1999, according to HMRC data reviewed by the Treasury Committee. Then, once the new tax year starts on 6 April, the pace eases off.

With that rush behind us, the middle of the year can be an easy time to let saving drift down the to-do list. That’s what makes this a good moment to step back and reflect on how our saving habits form.

If that sounds familiar, you’re not alone. Behavioural economists call this present bias – our tendency to prioritise what’s urgent today over what’s important tomorrow. Without an immediate deadline, even worthwhile financial decisions are easy to put off.

The problem is that waiting until the last minute can cost more than many people realise.

The hidden cost of waiting

Leaving your saving to the last-minute carries two quiet drawbacks.

The first is practical, and it catches people out every year. A deposit is not always instant. Depending on how you pay in – by bank transfer, debit card or from another provider – it can take time for the money to actually land and be counted within the tax year. If you leave your contribution until the evening of 5 April, there is a genuine risk it will not process in time, and the allowance you meant to use disappears anyway.

The second drawback is about growth. If your money is sitting somewhere that isn’t earning interest, you could be missing out for up to 11 months – particularly if you don’t intend to spend it. Spreading contributions through the year means your savings can start working sooner, giving them more time to benefit from tax-free interest.

There is also evidence that the deadline rush does not translate into fuller use of the allowance. A large share of savers use only a fraction of what they are entitled to each year – the average cash ISA deposit in 2023/24 was around £7,000, roughly a third of the £20,000 allowance. In other words, the panic to “do something” before 5 April can end with a modest deposit rather than a considered plan.

A calmer way to save

None of this means the ISA deadline is a bad thing. It is a useful prompt. The opportunity is to turn a once-a-year scramble into a habit that runs quietly in the background.

Here are a few ideas worth considering:

  • You don’t have to wait for the deadline – you can save into an ISA through the year. Many ISAs let you pay in whenever you like, so rather than scrambling with a lump sum in April, you can add money regularly across the year. Little and often is often easier to manage, and your savings start earning tax-free interest sooner.
  • Reached the limit on one account? You can usually open another. If you’ve used the funding window on a fixed rate ISA, you’re not stuck – you can open a new ISA and keep saving, as long as you stay within your overall £20,000 annual allowance. Some accounts only accept deposits for a short period after opening, so it’s worth checking the rules of yours and planning around them.
  • Give yourself a buffer. If you do prefer to top up near the deadline, aim to pay in a few days early so the money has time to be received and counted within the correct tax year.
  • Check where your allowance stands. A quick look at how much of your £20,000 you have used so far removes the guesswork and the last-minute surprise.

The point is not to save more than is comfortable. It is to remove the artificial urgency that the deadline creates, so that saving becomes a steady rhythm rather than an annual sprint.

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One more thing on the horizon

There is another reason to keep an eye on your allowance over the next year or so. From 6 April 2027, the amount that savers under 65 can pay into a cash ISA each year is due to fall from £20,000 to £12,000, while those aged 65 and over will keep the full £20,000.
Importantly, the overall £20,000 ISA allowance is not changing – for under-65s, any amount above £12,000 would need to go into other types of ISA, such as a stocks and shares ISA, to stay tax-free.

This would be the first cut to the cash ISA limit since the allowance was last changed, making the next couple of tax years a useful moment to think about how you want to use your allowance.”

Whether you save monthly or top up throughout the year, the important thing is not to wait for the deadline. A steady habit can help your money start working sooner and make saving feel much less like an annual sprint.

Your eligible deposits with OakNorth are protected up to £120,000 by the Financial Services Compensation Scheme (FSCS). Tax treatment depends on individual circumstances and may be subject to change in the future.