UK Treasury Proposes 20% Tax on Idle Cash in ISAs

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  //stocks-investing.news-articles.net/content/202 .. easury-proposes-20-tax-on-idle-cash-in-isas.html
  Published in Stocks and Investing on Wednesday, December 10th 2025 at 14:25 GMT by inews.co.uk
      Locale: UNITED KINGDOM

Don’t tax investors who hold cash in their stocks and shares ISAs – Reeves urges caution

A new proposal from the UK Treasury to tax cash that sits inside investment accounts, including stocks and shares Individual Savings Accounts (ISAs), has raised a storm of criticism from financial experts, policymakers and retail investors alike. In a piece published on MSN Money Canada, Reeves – a senior adviser at the Financial Policy Institute – argues that the move would disproportionately hurt prudent savers, reduce long‑term investment, and ultimately undermine the UK’s reputation as a world‑class financial hub.

What the Treasury’s proposal actually says

In its “Finance Bill 2024” the Treasury announced a “cash tax” that would apply to any cash held in an ISA, an innovative finance account, a business ISA or a self‑directed personal pension (SPP) that is not used for an active trading strategy. The tax is set at 20 % on the balance that remains idle for more than 12 months, with the intention of nudging investors to put their money to work in productive assets rather than letting it sit idle. The measure was first announced in the 2023 fiscal report and is still subject to parliamentary debate.

Reeves points out that the language of the proposal is deliberately broad – the government has yet to specify an exemption for cash that is held for “short‑term hedging” or for use as a liquidity buffer. Under the current wording, even a small amount of cash held within a stocks‑and‑shares ISA would be taxable after a year, regardless of its purpose.

Why the tax would hurt ordinary investors

1. Liquidity and risk management
   Most retail investors keep a portion of their portfolio in cash to cover emergencies, short‑term goals or to act as a cushion against volatility. By imposing a tax on that cash, investors would be forced to liquidate some of their equity holdings to avoid the penalty, thereby eroding portfolio performance.

2. Distortion of savings behaviour
   The cash tax would create a disincentive to keep funds in ISAs, which are currently the most tax‑efficient vehicles for long‑term saving. Investors might move their cash to less favourable accounts (e.g., a regular savings account with lower rates) simply to avoid the tax, reducing the flow of capital into UK‑based equities and bonds.

3. Unequal impact on lower‑income savers
   The tax is set to apply to the cash balance itself, not to gains or dividends. Consequently, savers who maintain modest ISA balances – often those with the least ability to diversify – would be penalised at the same rate as wealthy investors holding large cash reserves.

4. Administrative complexity
   ISAs are already subject to annual contribution limits (currently £20,000 for 2023). Adding a “cash tax” would require further reporting, verification and enforcement mechanisms that could increase costs for both trustees and investors.

Reeves’ counter‑arguments

Reeves draws on a 2022 survey by the Association of British Insurers that found 41 % of retail ISA holders keep a buffer of cash inside their portfolios. He argues that this behaviour is an investment strategy – a “liquidity provision” that protects investors from forced selling during market downturns. When the Treasury proposes a blanket tax, it disregards the risk‑management rationale behind holding cash.

Furthermore, Reeves cites the “Tax on Cash in Investment Accounts” case study in the U.S., where a similar measure was adopted in 2018 but was later repealed after a backlash from the investment community. He stresses that such a policy would likely backfire, driving savers to seek tax‑efficient accounts in other jurisdictions, thereby reducing the UK’s attractiveness as a global investment destination.

Broader policy context

The Treasury’s cash tax is part of a larger “productivity boost” agenda aimed at reducing the fiscal gap and encouraging productive capital allocation. The policy is linked to the broader “Cash‑in‑Investment Accounts” provision in the Finance Bill, which also proposes:

• Higher contribution limits for ISAs to encourage more saving.
• Tax‑free dividends for small‑cap equities.
• A dedicated fund for green bonds.

Reeves argues that a more balanced approach – for instance, raising ISA limits while providing tax relief for dividends and green bonds – would achieve the Treasury’s objectives without harming the savings base.

What the article says about possible alternatives

Reeves recommends several policy alternatives:

1. Increase the ISA contribution limit to £25,000 per year, thereby encouraging more capital to flow into equities without a punitive cash tax.
2. Introduce a “cash‑buffer” exemption for balances below a certain threshold (e.g., £5,000) or for those that have been held for less than 12 months.
3. Provide targeted tax relief for investments in green bonds and other “productivity” assets.
4. Invest in financial literacy programs that teach investors about risk management and the benefits of maintaining a cash buffer.

He concludes that the Treasury’s current proposal “fails to recognise the nuanced behaviour of retail investors” and could ultimately backfire by diminishing long‑term savings.

Final thoughts

The article ends on a note of caution: a policy designed to force money out of idle accounts into more “productive” assets may do the opposite if it discourages investors from keeping a liquid cushion or pushes them towards less efficient accounts. Reeves’ call to “don’t tax investors who hold cash in their stocks and shares ISAs” is grounded in a desire to preserve the UK’s savings culture, protect ordinary investors from punitive measures, and maintain the attractiveness of the UK’s tax‑efficient investment vehicles.

For investors reading the piece, the takeaway is clear: be aware that any forthcoming tax on cash inside ISAs could alter the cost structure of your portfolio and consider whether you are comfortable holding a cash buffer versus converting it into taxable gains. For policymakers, the article urges a nuanced approach that balances fiscal objectives with the behavioural realities of retail savers.