Savers are anxiously waiting to see if Chancellor Rachel Reeves will slash the Cash ISA allowance from £20,000 to £4,000 in her Spring Statement on March 26.

Her goal is to push more savers into riskier Stocks and Shares ISAs. But she’s picked a bad moment.

Stock markets are in turmoil, with US President Donald Trump rattling investors by threatening trade tariffs on Mexico, Canada, China, and the EU.

For many, this reinforces why they avoid investing in shares. Particularly pensioners who rely on stable cash interest to top up their state pension.

That said, those willing to accept some risk can expect better long-term returns from a Stocks and Shares ISA, albeit with volatility along the way.

But whether you favour cash or shares, one thing is certain: you must act before midnight on April 5.

Alice Haine, personal finance analyst at Bestinvest by Evelyn Partners, warns the consequences of missing the deadline are severe.

“ISAs offer a golden opportunity to shield your savings from the taxman, but if you don’t use yours by the deadline, it vanishes into thin air.”

Unlike some tax allowances, unused ISA allowances don’t roll over. “Once the clock strikes 12, any unused allowance is gone. No rollovers, no extensions, no second chances,” Haine stresses.

This year, April 5 falls on a Saturday, meaning some providers may require action before then. However, most should allow online applications right up to the wire.

With taxes at record highs, ISA tax breaks are more valuable than ever.

Income tax thresholds are frozen until 2028, capital gains tax (CGT) has tightened, and the dividend allowance has been slashed.

Haine said: “Money in an ISA is safe from income tax, CGT, and dividend tax for life. Why hand over more of your hard-earned cash to the Treasury?”

Each adult has their own £20,000 ISA allowance, so couples can shelter up to £40,000 if they have the funds.

This year, savers can still allocate the full amount to a Cash ISA, a Stocks and Shares ISA, or a blend of both.

But if speculation is correct and Reeves slashes the Cash ISA limit from April 6, that will no longer be possible.

The full £20,000 allowance may remain for Stocks and Shares ISAs, but Cash ISA contributions could be capped at £4,000.

As a result, many are likely to max out their Cash ISA allowance while they still can. Even those who might have otherwise opted for stocks.

But there’s a potential pitfall here, too.

Reeves hopes to boost the UK economy by funnelling more savings into the FTSE, boosting British businesses.

However, most of the money going into Stocks and Shares ISAs goes into foreign markets, particularly the US.

In effect, the Treasury is offering tax breaks to invest in overseas competitors. That policy seems flawed to me.

This raises another possibility: could Reeves restrict Stocks and Shares ISA tax benefits to UK shares only?

This is pure speculation by me. But those who save my view might consider prioritising foreign investments while they still qualify.

Either way, Alice Haine’s message is stark: don’t miss the deadline. No rollovers, no extensions, no second chances.