HMRC ISA Tax Changes 2026 Explained: New 22% Charge, Lower Cash Limit and What It Means For You

HMRC has confirmed a major overhaul of Individual Savings Account rules that will affect millions of UK savers from April 2027. The changes, announced this week, include a new 22 percent tax charge on cash held inside Stocks and Shares ISAs and a significant reduction in the annual Cash ISA allowance for under-65s. Here is everything you need to know about the new ISA rules and what they mean for your savings.

What Are the New HMRC ISA Rules?

The most significant change confirmed by HMRC is the introduction of a flat-rate 22 percent tax charge on any interest earned on cash held inside a Stocks and Shares ISA or an Innovative Finance ISA. Until now, any interest earned inside an ISA wrapper has been completely tax-free. From 6 April 2027, that will no longer apply to uninvested cash sitting inside investment accounts.

At the same time, the annual Cash ISA allowance for people under the age of 65 will be cut from £20,000 to £12,000. The overall ISA allowance of £20,000 per year remains unchanged, meaning savers can still put up to £20,000 into ISAs in total  but no more than £12,000 of that can go into a Cash ISA if you are under 65. Savers aged 65 and over will continue to benefit from the full £20,000 Cash ISA allowance.

Key Changes at a Glance

The new rules coming into effect from 6 April 2027 include four main changes. First, a 22 percent charge will apply to interest earned on cash held within Stocks and Shares ISAs and Innovative Finance ISAs. Second, the annual Cash ISA limit for under-65s drops from £20,000 to £12,000. Third, transfers from Stocks and Shares ISAs into Cash ISAs will be blocked for savers under 65 — though transfers in the other direction, from Cash ISAs into investment accounts, will still be permitted. Fourth, investors will no longer be allowed to hold portfolios consisting entirely of money market funds inside a Stocks and Shares ISA.

Why Is the Government Making These Changes?

The government's stated objective is to encourage more Britons to move away from cash savings and into long-term investing. Chancellor Rachel Reeves and the Treasury argue that savers holding large amounts of cash in tax-advantaged accounts are missing out on higher long-term returns that come from investing in stocks and shares.

Research consistently shows that long-term investors have historically achieved better returns than cash savers, although investing always carries risk and returns are never guaranteed. By making Cash ISAs less attractive and penalising large cash balances inside investment accounts, the government hopes to shift more capital into financial markets and ultimately support economic growth.

Industry Backlash  Are the Changes Fair?

The new ISA rules have sparked significant criticism from the financial services industry. Rachel Vahey, head of public policy at AJ Bell, described the reforms as riddled with unintended consequences and argued that they reduce the flexibility savers have relied on for years. She warned that the changes could actually discourage new investors rather than encourage them.

Simon Harrington of PIMFA said the industry remained disappointed that the government had chosen to introduce what he described as draconian anti-avoidance measures with little evidence that consumers would behave in the way the policy assumes. Brian Byrnes of Moneybox added that introducing restrictions before the changes take effect in 2027 risks creating unnecessary confusion and problems for savers.

Industry figures have also raised concerns about savers who use cash inside investment accounts for legitimate reasons  for example, to hold dividend income before reinvesting, or to manage the timing of trades. Under the new rules, these savers could face unexpected tax charges on what is essentially working capital within their investment accounts.

What Should Savers Do Now?

The new rules do not come into force until 6 April 2027, which means savers still have time to plan. For the current tax year, the existing rules apply  you can still put up to £20,000 into Cash ISAs if you are under 65, and any interest earned inside your ISA remains completely tax-free.

If you currently hold large amounts of uninvested cash inside a Stocks and Shares ISA, it is worth speaking to a financial adviser about whether that strategy remains appropriate under the new rules. HMRC has confirmed that small cash buffers  for example, cash waiting to be invested following a dividend payment  may be exempt from the interest charge, though full details are yet to be confirmed.

It is also worth noting that HMRC plans to consult on the draft legislation before the changes take effect, meaning some aspects of the rules could be softened in response to industry feedback. The regulations are expected to be laid before parliament in the Autumn.

The Bottom Line

The HMRC ISA changes represent the most significant overhaul of the UK savings landscape in over a decade. Millions of savers will need to rethink how they use their ISA allowances from April 2027, particularly those who rely on Cash ISAs as their primary savings vehicle or who hold significant cash balances inside investment accounts.

For now, the best approach is to make the most of the current rules while they last, stay informed as HMRC publishes further guidance throughout 2026 and consider taking professional financial advice if you are unsure how the changes affect your personal situation.