Cash ISA Calculator 2027
See what the new Cash ISA limit means for your savings
Compare how much new cash you can shelter under current rules and from 6 April 2027, then estimate any extra tax if the rest sits outside a Cash ISA.
From 6 April 2027
If you are under 65, the annual Cash ISA limit falls to £12,000.00. If you are 65 or over, it stays £20,000.00. Existing Cash ISA balances are not forced out. This calculator compares current rules with the April 2027 rules.
New money only. Do not include money already sitting in an ISA.
Common amounts:
Annual rate on the savings you are modelling.
Common rates:
Use the age you will be at the end of the tax year. Enter 65 if you turn 65 during that year.
Annual income that is not savings interest, for example salary or pension. Used to work out your tax-free savings allowance.
Common incomes:
Your Cash ISA estimate
From April 2027
The 2027 Cash ISA change is not expected to cost you extra tax on these figures.
Current rules
£0.00
Cash ISA limit £20,000.00
From 6 April 2027
£0.00
Cash ISA limit £12,000.00
Why these figures differ
About £8,000 of new savings may sit outside a Cash ISA from April 2027, but your tax-free savings allowance still covers the estimated interest, so extra tax looks £0.
You may still have about £8,000.00 of overall ISA allowance left for a Stocks and Shares ISA. This estimate assumes overflow stays in a normal taxable savings account.
Estimate for new annual contributions only. Existing ISA balances are not removed by the April 2027 limit. For tax on savings interest in more detail, use the Savings Tax Calculator.
From 6 April 2027 breakdown
Where new savings go
Interest and tax
Showing the from-6 April 2027 Cash ISA limit and 2027/28 savings tax rates on interest outside a Cash ISA.
Key Cash ISA figures
£20,000.00
Current Cash ISA limit
£12,000.00
From Apr 2027 if under 65
£20,000.00
Overall ISA allowance
About the Cash ISA Calculator 2027
Use this Cash ISA calculator to see what the April 2027 Cash ISA limit means for your savings. It compares how much new cash you can put into a Cash ISA under current rules and from 6 April 2027.
Enter how much you plan to save, your interest rate, your age and your income. The calculator estimates how much still fits in a Cash ISA, how much may sit outside, and any extra tax on that interest.
Official sources: Cash ISA limit reduction (GOV.UK), ISA reform 2027 factsheet, and Individual Savings Accounts.