ISA vs Savings Calculator
Is a cash ISA actually worth it? Put in the same deposit, monthly amount and rate for both, and see exactly how much tax a taxable savings account would cost you above the Personal Savings Allowance, and what that costs you over the years.
Estimate only. Estimate, assumes fixed growth/rates; investments can fall; not financial advice.
Enter a deposit or monthly amount
Add a starting deposit or a monthly contribution and we'll compare the ISA and taxable savings balances.
Why an ISA can beat an ordinary savings account
Interest in a cash ISA is always tax-free, however much you earn. Interest in an ordinary savings account is only tax-free up to your Personal Savings Allowance, £1,000 a year for basic-rate taxpayers, £500 for higher-rate, and nothing at all for additional-rate taxpayers. Anything earned above that allowance is taxed at your marginal rate every single year, which means a taxable account doesn't just lose that year's tax, it compounds more slowly every year after, because the tax is skimmed off before it has a chance to grow. This calculator runs the same deposit, monthly contribution and rate through both accounts and totals up exactly how much tax you'd pay, year by year, in a taxable account. The current £20,000 annual ISA allowance covers most savers comfortably, but it isn't modelled as a hard limit here, check gov.uk if you're contributing more than that in a single tax year.
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