Your Cash ISA Earns 4.51% and CPI Just Fell to 2.8%. The Government Is Cutting Your Allowance Anyway.

Trading 212 offers 4.51% on its easy-access Cash ISA. That is not a promotional teaser — it has held near that level since spring 2026, supported by a Bank of England base rate that has sat at 3.75% for six consecutive meetings and may now go higher. For a full breakdown of ISA types and limits, see our ISA hub.

For a basic-rate taxpayer, a 4.51% tax-free ISA return is equivalent to 5.64% in a taxable account. A higher-rate taxpayer would need 7.52% from a standard savings account to match it. Those numbers do not exist anywhere in the UK savings market.

The FTSE 100 has delivered roughly 7.2% annualised over 40 years. But that average conceals drawdowns of 48% (2008), 34% (2020), and the 14-month flatline of 2022. An average is not a guarantee — it is a statistic. A 4.51% Cash ISA is a guarantee. And in a world where UK business confidence just hit a five-year low, guarantees are not boring. They are expensive. Check our savings hub for the latest best-buy Cash ISA rates updated weekly.

The Treasury's rationale for cutting the Cash ISA allowance is that £300 billion sitting in cash ISAs is 'unproductive.' That framing is revealing. The government does not see your capital preservation as a policy success. It sees it as a drag on growth that it can redirect into equities — and the tax revenue those equities generate.

But the MSE analysis confirms that easy-access ISAs are currently paying more than equivalent taxable savings accounts. This is unusual. It means the ISA wrapper is not just tax protection — it is genuinely the best rate on offer. Removing £8,000 of annual capacity from that wrapper is not nudging. It is shoving.

And who gets hurt? Not the wealthy, who will simply shift their allocation to stocks or use their full £20,000 S&S ISA allowance. The people who lose are the ones who use a Cash ISA as their primary savings vehicle: first-time buyers building a deposit, retirees managing sequence-of-returns risk, anyone who has already watched a market fall wipe out years of gains and decided never again.

Consider what this means for a saver who started filling a Cash ISA in their 30s. Over 30 years, the difference between £20,000 and £12,000 of annual tax-free capacity is £240,000 of principal that sits outside the wrapper, exposed to tax. At 4.51%, that generates nearly £11,000 of interest annually — and for a higher-rate taxpayer, roughly £4,000 of that goes to HMRC. The allowance cut is not a one-year inconvenience. It is a compound tax bill disguised as simplification.

Inflation at 2.8% (CPI, May 2026, ONS) makes the arithmetic straightforward. A 4.51% Cash ISA minus 2.8% CPI equals a 1.7% real return. That is not exciting. But it is positive — and positive real returns on cash have been rare for a generation.

Compare that to a Stocks & Shares ISA in a down year. The FTSE 100 fell 14% in 2018. It fell 11% in 2022 (total return basis). In those years, the cash saver earned 1.7% real while the equity investor lost purchasing power equivalent to three or four years of dividends.

For context on how the FTSE 100 has actually performed against cash over the long run, see our deep-dive analysis of 40-year FTSE returns.

The stock market's long-run average is mathematically true and practically useless if you need the money in 2028 for a house deposit. The cash ISA does not care about your time horizon. It pays the same rate whether you withdraw next month or never touch it. That flexibility is worth a lot more than the difference between 7.2% and 4.51% — especially when the 7.2% is not guaranteed to show up in any given year.

From April 2026, the dividend tax rate for basic-rate taxpayers rose from 8.75% to 10.75%. For higher-rate taxpayers, it went from 33.75% to 35.75% — on the same £500 dividend allowance that has not budged since 2024.

This matters because the standard pitch for a Stocks & Shares ISA is 'tax-free dividends.' But the dividend tax increase means that outside an ISA, dividend income is now taxed more heavily. That makes the ISA wrapper more valuable — but it also makes the UK equity market less attractive as an asset class. If corporate behaviour shifts toward buybacks and away from dividends because the tax treatment has worsened, the UK equity income case weakens.

The Cash ISA avoids this entire debate. You do not need to guess whether UK plc will keep paying 3.5% dividend yields under a new tax regime. You get 4.51%, every month, regardless of what HMRC does next. For the opposite view, read why the FTSE 100's 7.2% track record makes cash look expensive.

The Financial Services Compensation Scheme protects cash deposits up to £120,000 per banking licence. That is your Cash ISA. If the bank fails, you get your money back within seven working days.

A Stocks & Shares ISA is protected to £85,000 — and only against firm failure, not investment loss. If your FTSE 100 tracker drops 30%, the FSCS will not send you a cheque. That is market risk, not counterparty risk, and you carry it alone.

At today's rates, £120,000 in a 4.51% Cash ISA generates £5,412 a year in tax-free interest. That is not a retirement strategy. But it is a genuine, insured, predictable income stream that no equity portfolio can replicate without taking on risks that are fundamentally different in kind, not just degree.

It is worth understanding the distinction clearly because the marketing materials for investment platforms often say "FSCS protected" without specifying that the protection covers administrative failure — not a bear market. The FCA's own guidance makes this explicit. Cash ISAs get the stronger guarantee because they are deposits, not investments. That asymmetry exists for a reason: the regulator understands that cash savers and equity investors are carrying fundamentally different risks. The ISA allowance cut collapses that distinction, treating all £20,000 of your annual capacity as if it should be exposed to market forces. It should not.

You have until 5 April 2027 to use your full £20,000 Cash ISA allowance. From 6 April 2027, unless you are over 65, that number drops to £12,000 — a 40% cut. There is no phase-in, no taper, no grandfathering of existing balances. The allowance disappears.

This is not theoretical. The legislation is drafted. The HMRC rates and allowances tables already reflect the new tax year structure. The Treasury is not bluffing.

If you have £20,000 of capacity this year and you use only £12,000, you have permanently lost £8,000 of tax-free shelter. That capacity compound — £8,000 at 4.51% over 20 years is nearly £19,500. You are not just losing this year's allowance. You are losing two decades of tax-free compounding on money that could have been inside the wrapper.

The stock market will still be there in April 2027. The Cash ISA allowance will not.