A new debate over a possible ISA “loophole” has highlighted the complexity created by the Government’s planned reforms to cash and investment ISAs.
From 6 April 2027, savers who hold cash inside a stocks and shares ISA, or another non-cash ISA, will face a 22% charge on interest earned on that cash. The change is designed to stop people bypassing the new £12,000 annual cash ISA limit for under-65s by placing money in an investment ISA and simply leaving it uninvested.
The policy is part of the Government’s wider attempt to encourage more people to invest rather than keep large sums in cash. But the latest discussion has focused on whether savers may still be able to avoid the charge by using money market funds and holding only a small amount in another qualifying investment.
That debate matters because it shows the tension at the heart of the reforms. Ministers want to push more money into productive investment, but savers and platforms are now being asked to navigate a more technical ISA system than many expected.
What is the 22% charge?
The 22% charge will apply to interest, or alternative finance returns, paid on cash held inside non-cash ISAs. This includes stocks and shares ISAs and innovative finance ISAs.
It does not mean that ordinary cash ISA interest will be taxed within the £12,000 cash ISA allowance for under-65s. Nor does it mean that investment returns inside stocks and shares ISAs will generally lose their tax-free status.
The aim is narrower. The Government wants to prevent people from using a stocks and shares ISA as a substitute cash ISA once the cash ISA limit is reduced.
At present, many investment platforms allow investors to hold uninvested cash inside a stocks and shares ISA. That can be useful. Investors may be waiting to buy shares or funds, may have sold investments and not yet reinvested, or may want a temporary cash balance during uncertain market conditions.
From April 2027, that cash can still be held inside a non-cash ISA, but any interest paid on it will face the 22% charge.
Why the Government is making the change
The Government’s broader policy objective is to encourage a stronger investment culture in the UK.
The overall adult ISA allowance will remain £20,000. However, under-65s will only be able to put £12,000 of that into a cash ISA from April 2027. The rest of the allowance can still be used for stocks and shares ISAs, innovative finance ISAs or other qualifying ISA products.
The Government argues that more people should consider long-term investing, especially where they have savings beyond short-term emergency needs. Over time, investing has the potential to deliver higher returns than cash, although it also involves risk and the value of investments can fall.
The policy also fits a wider economic ambition. Ministers want more household savings to flow into capital markets, supporting businesses, investment and growth.
The difficulty is that behaviour does not always change simply because rules change. Some cautious savers may not move into investments. They may instead hold more money in ordinary savings accounts, reduce saving, or become frustrated by a system they perceive as less simple.
The money market fund question
The latest controversy concerns money market funds.
Money market funds are investment funds that hold short-term, high-quality debt instruments. They are often used as relatively low-risk, cash-like investments, although they are still investments and are not the same as a bank or building society deposit.
Under the Government’s anti-circumvention rules, cash-like assets will still be allowed within non-cash ISAs, but an ISA portfolio made up entirely of money market funds will not be permitted.
That wording has led to discussion about whether investors could put most of their non-cash ISA into a money market fund and a very small amount into another qualifying investment, such as a conventional fund, ETF or individual share, to avoid falling foul of the 100% cash-like asset restriction.
The technical answer may depend on the final legislation and provider rules. The Government has said a technical consultation with the industry will take place before regulations are laid. That means savers should be cautious about treating any suggested loophole as settled planning.
More importantly, a strategy that is technically compliant may not always be suitable. Money market funds carry different risks from cash deposits. They can be useful for some investors, but they should not be treated as a perfect replacement for cash savings.
Why critics are concerned
Critics argue that the reforms risk making ISAs harder to understand.
The original attraction of ISAs was their simplicity. Savers could put money into a tax-efficient wrapper and understand, broadly, that interest, dividends and gains would not be taxed. Over time, the ISA landscape has become more complicated, with cash ISAs, stocks and shares ISAs, Lifetime ISAs, innovative finance ISAs, transfer rules, age-based limits and now new anti-avoidance rules.
The Treasury Committee has previously warned that cutting the cash ISA allowance may not necessarily persuade people to invest. Its chair, Dame Meg Hillier, said the Treasury’s ambition was commendable, but questioned whether the reforms would drive the cultural change ministers want and warned that they could confuse consumers.
MoneySavingExpert founder Martin Lewis has made a similar point, arguing that encouraging investment is a worthwhile aim, but that the Government should use a “carrot, not stick” approach.
That criticism is important because trust is central to financial behaviour. If savers feel the system is being made more difficult or less predictable, they may become less willing to engage with investment at all.
The Government’s case is not without merit
The Government’s objective should not be dismissed.
The UK does have a long-running issue with low retail investment participation compared with some other advanced economies. Many households hold large balances in cash even when they may have long-term financial goals. Over long periods, that can reduce potential returns and leave savings more exposed to inflation.
There is also a wider economic question. If more domestic savings were invested in productive assets, the UK could potentially improve access to capital for companies and support long-term growth.
From that perspective, the ISA reforms are part of a broader attempt to connect household saving with national investment needs.
The problem is execution. A reform can have a sound policy objective but still be difficult to implement well. If the new rules are too complex, they could discourage the very behaviour they are intended to promote.
What savers should understand
The practical message for savers is that the reforms are not immediate. They are due to take effect from 6 April 2027, and further detail is expected through consultation and regulations.
For now, the main points are clear. The overall adult ISA allowance is expected to remain £20,000. The annual cash ISA limit for under-65s will fall to £12,000. Those aged 65 and over will retain the £20,000 cash ISA allowance. Cash held inside a non-cash ISA will still be allowed, but interest on that cash will face a 22% charge. Money market funds may still be used, but not as 100% of a non-cash ISA portfolio.
Savers should also avoid making decisions based only on tax treatment. Cash, money market funds and long-term investments serve different purposes. Cash is suitable for emergency funds and short-term needs. Investments may be suitable for longer-term goals, but they involve risk.
A rule that nudges people towards investing does not remove the need to understand risk, time horizon and personal circumstances.
A strategic lesson in policy design
The ISA reforms offer a useful business and policy lesson: incentives must be simple enough for people to act on them.
The Government wants to change saver behaviour. Businesses often face the same challenge when they want customers, staff or investors to adopt a new approach. The design of the incentive matters. If the incentive is too complicated, people may disengage. If it feels punitive, they may resist. If it is easy to understand and clearly beneficial, behaviour is more likely to change.
The debate over money market funds shows how quickly rules can produce new workarounds, edge cases and uncertainty. That does not mean anti-avoidance rules are unnecessary, but it does show the cost of complexity.
The stronger long-term approach would be to make investing easier, cheaper and better understood, rather than relying mainly on restrictions around cash.
A reform that still needs careful handling
The Government is right to ask whether the ISA system should do more to support long-term investment. But it must also preserve confidence in a product that many people value because it is simple and predictable.
The new 22% charge is intended to stop people using investment ISAs as disguised cash ISAs. That objective is logical. But the discussion around potential loopholes suggests the reforms may already be creating a more complicated system.
For savers, the key is not to chase technical shortcuts, but to understand what each product is for. For policymakers, the key is to ensure that rules designed to encourage investment do not become so complicated that they discourage participation altogether.
The ISA system has been one of the UK’s most successful savings products. The challenge now is to modernise it without undermining the simplicity that made it successful in the first place.
