ISA Switch Calculator
Our ISA switch calculator shows how much extra return you could earn by moving your ISA from your current rate to a higher one. Even a seemingly small rate improvement compounds significantly over time — and unlike other savings accounts, ISA transfers preserve your tax-free status without using up any of your current year allowance.
ISA Switch Calculator
See how much more interest you could earn by switching to a better-rate ISA.
How ISA Transfers Work
You can transfer an existing ISA to a new provider at any time without losing the tax-free status or counting toward the current year allowance. To preserve the tax-free status, you must use an official ISA transfer — never withdraw the money and re-deposit it in a new account, as this uses your annual allowance and any amount above £20,000 cannot re-enter the ISA wrapper.
Transfers must be handled directly between providers. Request a transfer form from the new provider, who will contact your existing provider and arrange the movement. The process typically takes 15–30 working days for cash ISAs. During the transfer period, you cannot contribute to either ISA.
The Cost of Loyalty
Many ISA holders leave money in accounts earning well below the best available rates — a phenomenon known as loyalty penalty. If your ISA is earning 2% while the best accounts pay 4.5%, the difference on £30,000 over 5 years is approximately £4,200 in lost interest. Checking your ISA rate annually against the best available takes minutes and can be worth thousands over a lifetime of saving.
This calculator makes the case visible: enter your current balance, current rate, potential new rate, and time horizon to see exactly what staying put is costing you versus switching. After reviewing the numbers, you can return to our Savings Calculator to model the long-term growth at the improved rate.
Frequently Asked Questions
Yes. You can transfer between ISA types as well as between providers. Moving from stocks and shares to cash ISA sells the investments and transfers the cash — timing the sale carefully to avoid selling at a loss in a down market. Moving from cash to stocks and shares ISA invests the transferred cash in your chosen funds.
Some fixed-term cash ISAs carry an early withdrawal penalty if transferred before the fixed period ends — typically loss of a number of days interest. Check your current ISA terms before initiating a transfer. Easy-access ISAs generally have no transfer penalty.
For current-year contributions, you must transfer the whole amount subscribed in the current year (though you can leave previous-year funds). For previous-year ISA funds, partial transfers are allowed by HMRC rules, though not all providers accept partial transfers — check before applying.
Easy-access cash ISA rates from the best providers are currently around 4.5–5% AER. Fixed-term cash ISAs (1–5 year) offer similar or slightly higher rates. Rates change frequently — compare on financial comparison sites using AER for a true like-for-like comparison.
ISA transfers do not use any of your annual £20,000 allowance. Only new contributions in the current tax year count toward the allowance. You can transfer any amount accumulated in previous years without allowance implications. Our ISA Calculator projects the long-term growth on any starting balance at the new rate.
Enter the balance in your current ISA, the existing rate, and the rate offered by the new ISA provider. The calculator shows the interest difference annually and the accumulated saving over your chosen period. ISA transfers preserve your tax-free status — you must use an official ISA transfer rather than withdrawing and redepositing, which would use your current year’s allowance. Transfers typically take 15 working days for cash ISAs and longer for stocks and shares. During the transfer period, no interest is usually paid, so factor this into the comparison — a slightly higher rate may not compensate for a long transfer period if it is a significant amount. Most providers now offer flexible ISAs that allow withdrawals and redeposits within the same tax year without affecting the annual limit.
Important Information
This calculator is provided for general information and planning purposes only. It does not constitute financial or tax advice and should not be relied upon as such. Figures are indicative estimates based on simplified, publicly available criteria and stated assumptions. Actual results depend on your full circumstances. See our Disclaimer for further information.