ISA Reform 2027: The Cash ISA Limit Is Being Cut — What Should You Do Now?

The government has confirmed one of the most significant changes to the ISA regime in years: from 6 April 2027, the annual cash ISA allowance for savers under 65 will be cut from £20,000 to £12,000. The remaining £8,000 of the total £20,000 ISA allowance will need to go into a Stocks and Shares ISA or Innovative Finance ISA. Savers aged 65 and over are unaffected — they retain the full £20,000 cash ISA allowance.

This is a deliberate policy choice to push younger savers toward investing rather than holding cash. Whether or not you agree with the philosophy, the rules are changing. Here's what they mean and what you should do before April 2027.

What's Changing and Why

The government's stated rationale is that too many savers leave money in low-yielding cash ISAs for decades rather than investing for long-term growth. Ministers argue that the Stocks and Shares ISA wrapper offers greater potential to build wealth over time, and that encouraging younger savers into the market — particularly via low-cost index funds — will produce better outcomes than holding cash indefinitely.

The reform also introduces an anti-circumvention rule: transfers from Stocks and Shares or Innovative Finance ISAs into Cash ISAs will be banned from April 2027. Currently you can transfer freely between ISA types — this will no longer be possible in one direction. Additionally, a 22% flat-rate charge will apply to interest earned on cash held within a non-Cash ISA, to discourage large cash holdings inside Stocks and Shares wrappers.

What This Means for Existing Cash ISAs

Existing cash ISA balances are not affected. Money already in a cash ISA before April 2027 can stay there, continue earning interest tax-free, and grow without limit. The new rules only affect new contributions from 6 April 2027 onwards.

If you're already using your full £20,000 ISA allowance in cash, you'll need to direct £8,000 of it into a different ISA type from next tax year, or simply save less into an ISA.

The Argument for Investing More

The historical case for Stocks and Shares ISAs is strong. The FTSE 100 has delivered average annual returns of around 7–8% over the long term (including dividends), compared to today's best cash ISA rates of around 4–4.5%. Over a 20-year period, £10,000 invested in a global index tracker at 7% annual growth becomes roughly £38,700; the same sum in a 4% cash account becomes £21,900.

The Vanguard LifeStrategy range, iShares Core MSCI World ETF, and Fidelity Index World Fund are widely cited as low-cost, diversified starting points for ISA investors. Total expense ratios (TERs) typically range from 0.07% to 0.22% per year — compared to actively managed funds that charge 0.75–1.5%.

The Argument for Keeping Cash

For short-term goals — a house deposit, emergency fund, or money needed within five years — cash ISAs remain appropriate. Markets can fall 30–50% in a downturn, and someone who needs their money in two years cannot afford to wait for recovery. The new £12,000 cash ISA limit is still generous enough to house a meaningful emergency fund.

For comparison, the US Roth IRA has a combined contribution limit of $7,000 per year for under-50s, with no equivalent of the UK's separate cash ISA. Australian superannuation allows concessional contributions of AU$30,000/year, but it's locked away until retirement.

What to Do Before April 2027

The 2026/27 tax year (ending 5 April 2027) is your last chance to put up to £20,000 into a cash ISA. If you have the savings capacity and want to hold cash long-term in a tax-free wrapper, maximising this year's cash ISA contribution makes sense.

After April 2027, plan your strategy: use the £12,000 cash ISA allowance for short-term savings and emergency funds, and direct the remaining £8,000 into a Stocks and Shares ISA invested in a low-cost global index fund if your timeline is five or more years.

Note: transfers between ISA types remain permitted to a Cash ISA until April 2027. If you want to move any existing Stocks and Shares ISA funds into cash, you have until then to do so.

Key Numbers

• Current ISA allowance (2026/27): £20,000 — all can go to cash
• New cash ISA limit from April 2027 (under 65): £12,000
• Over-65 cash ISA allowance: unchanged at £20,000
• Best cash ISA rate June 2026: ~4.5%
• FTSE 100 long-term average return: ~7–8% per year
• 22% flat charge on interest in non-Cash ISA cash holdings from April 2027

Sources

• NatWest – Cash ISA Limit Change from April 2027
• GOV.UK – ISA Reform 2027 Anti-Circumvention Factsheet
• Hargreaves Lansdown – ISA Allowance 2026/27
• Curvo – FTSE 100 Historical Performance

Educational content only — not financial advice.