Why experts say acting early on your ISA is crucial

At the start of each tax year, UK adults receive a fresh £20,000 Individual Savings Account allowance. This can be used across cash ISAs, stocks and shares ISAs and other variants, allowing savings and investments to grow free from income tax and capital gains tax. However, the allowance comes with a strict condition. It must be used within the tax year running from 6 April to 5 April, or it is lost permanently.

This “use it or lose it” rule is one of the key reasons financial experts are urging savers to act early rather than waiting until the deadline.

Tomos Russell, Portfolio Manager at Wealthify, said:

“Utilising your ISA allowance early in the tax year can help maximise your returns. If you don’t use it before the tax year ends, the unused allowance is lost.

Investing sooner gives your money more time to grow, and allows you to benefit from compounding — essentially earning returns on your returns over time.

Waiting until the end of the tax year may limit this snowball effect and reduce potential growth.”

His comments reflect a growing shift in how ISAs are viewed. Rather than being a last minute tax planning tool, they are increasingly seen as a long term strategy where timing is crucial.

The scale of ISA use in the UK underlines their importance. Around 15 million adults paid into an ISA in the 2023 to 2024 tax year, with total contributions reaching approximately £103 billion, the highest level in more than a decade.

At the same time, the total value of ISA holdings has risen to around £872 billion, with projections suggesting this could soon approach £1 trillion as contributions continue to grow.

Despite this surge, many savers still delay contributions until the final weeks of the tax year. Experts warn this approach can significantly reduce long term returns.

The key reason is compounding. When money is invested earlier, it has more time to generate returns. Those returns can then be reinvested, producing further gains in subsequent years. Over time, this creates a powerful cumulative effect.

Even relatively small timing differences can have a measurable impact. A saver who consistently invests their full £20,000 allowance at the start of each tax year will benefit from an extra 12 months of growth compared with someone who waits until the end. Over a decade or more, this difference can translate into thousands of pounds in additional returns.

The importance of acting early is becoming even more pronounced in the current economic environment. Rising interest rates have boosted returns on savings, but they have also increased the number of people paying tax on those returns. Savings tax receipts have surged to more than £6 billion annually, reflecting how many households are now affected.

With personal savings allowances frozen, even modest balances can generate taxable income outside an ISA. This has made tax efficient wrappers more valuable than ever.

At the same time, there is growing concern that too much money remains in low returning cash accounts. Estimates suggest around £300 billion is held in cash ISAs, where returns may struggle to keep pace with inflation over the long term.

While cash ISAs remain popular, experts increasingly point to stocks and shares ISAs as a way to achieve stronger long term growth, particularly when combined with early and consistent investing.

Policy changes are also adding urgency. From April 2027, the amount that can be held in cash ISAs is expected to fall to £12,000 for those under 65, while the overall £20,000 allowance remains unchanged.

This shift is designed to encourage more investment, but it also means savers who prefer cash will have less flexibility in future. Acting early now allows individuals to take full advantage of current rules before they change.

The cost of ISA tax relief highlights their value. The government estimates that ISAs will cost the Exchequer around £9.4 billion in 2024 to 2025, underlining how significant the benefits are for savers.

For individuals, this represents an opportunity to maximise tax free growth at a time when other allowances remain frozen.

There is also growing evidence of what long term ISA investing can achieve. Thousands of ISA millionaires have built substantial portfolios over time by consistently using their allowance and allowing returns to compound.

These outcomes are rarely the result of short term decisions. Instead, they reflect sustained contributions made early and often.

The message from experts is increasingly clear. ISAs should not be treated as a last minute financial task but as a long term strategy where timing matters.

Starting early in the tax year gives savers more time in the market, increases the potential for compounding and reduces the risk of missing out on the allowance altogether.

With a £20,000 limit available, rising tax pressures and significant policy changes on the horizon, acting early on an ISA is no longer just good advice. It is becoming essential for anyone looking to maximise their long term financial growth.