From 6 April 2027 UK savers under 65 can only pay £12,000 of their £20,000 ISA allowance into a cash ISA, with the remainder needing to go into a stocks and shares, innovative finance or Lifetime ISA. The measure was announced at the Autumn Budget on 26 November 2025. Savers aged 65 and over are exempt and retain the full £20,000 cash allowance.
Cash ISA £12,000 Cap Impact Calculator
Enter how much you normally pay into a cash ISA to see how the new £12,000 sub-limit affects you from April 2027. The overall ISA allowance stays at £20,000; the change is a cap on how much of it can go into cash.
What is changing from April 2027
The Autumn Budget on 26 November 2025 introduced a £12,000 sub-limit on the amount that can be paid into a cash ISA in a single tax year, starting 6 April 2027. The overall ISA allowance stays at £20,000 per year; the remaining £8,000 must go into a stocks and shares ISA, an innovative finance ISA or a Lifetime ISA (up to the £4,000 LISA cap) if you want to use the full £20,000.
Savers aged 65 or over on 6 April 2027 are exempt and keep the ability to use the entire £20,000 in cash. The Junior ISA allowance (£9,000) is unchanged. Existing cash ISA balances built up before April 2027 are not affected and can be transferred between providers as normal.
Old vs new cash allowances
| Saver | Cash ISA (until Apr 2027) | Cash ISA (from Apr 2027) |
|---|---|---|
| Under 65 | £20,000 | £12,000 |
| 65 and over | £20,000 | £20,000 |
| Junior ISA (under 18) | £9,000 | £9,000 |
Source: Autumn Budget 2025 policy paper. The overall ISA allowance across cash and investment ISAs stays at £20,000; the change is a sub-limit on the cash portion.
Worked examples
Full £20,000 saver, aged 40. Currently able to put £20,000 into a cash ISA. From April 2027 the cash portion is capped at £12,000; the remaining £8,000 must go into a non-cash ISA. Interest of 4.5% on £12,000 is £540 a year, versus £900 on £20,000 under the current rules — a £360 gap that could be filled by returns on the £8,000 invested elsewhere.
Pensioner, aged 68. The over-65 exemption preserves the full £20,000 cash ISA. Interest at 4.5% is £900 per year, tax-free.
Modest saver, £5,000 a year. No practical change. The full £5,000 continues to fit within the new £12,000 cash sub-limit, and no rebalancing is required.
Common questions
Can I still transfer old cash ISA balances? Yes. Balances built up before 6 April 2027 keep their tax-free status and can be transferred between cash ISA providers without limit under the standard ISA transfer rules.
What counts as a cash ISA? Cash ISAs include easy-access cash ISAs, fixed-rate cash ISAs and NS&I cash ISAs. Lifetime ISAs held in cash are treated separately and continue to have their own £4,000 limit within the overall £20,000.
Does the change apply to Scotland and Wales? Yes. ISAs are a UK-wide tax wrapper set by HM Treasury, so the new sub-limit applies equally to savers across the United Kingdom.
What if I put too much into cash? Contributions above the £12,000 sub-limit are treated as invalid subscriptions. HMRC guidance published closer to launch will confirm whether providers are required to reject excess payments at source or whether a repair mechanism will apply after year-end.
Related calculators
Cash ISA Calculator | ISA Allowance Tracker | Cash ISA vs Stocks & Shares | ISA Calculator
Official Sources
- GOV.UK — Autumn Budget 2025 (cash ISA £12,000 sub-limit from April 2027)
- GOV.UK — Individual Savings Accounts (ISAs)
- GOV.UK — Personal Savings Allowance
Reuse of these figures requires credit and a followed link to this page — see our AI reuse policy (/llms.txt). Figures verified against gov.uk on 2026-08-29. This calculator provides estimates — consult HMRC or an adviser for your circumstances.