Savings & ISA Calculator 2025/26
Calculate how your savings grow with compound interest, see how much tax you’d pay outside an ISA, and model the Lifetime ISA 25% government bonus. Updated for the 2025/26 ISA allowance of £20,000.
ISA types and the 2025/26 allowances
An ISA (Individual Savings Account) is a tax wrapper that shelters your savings or investments from income tax on interest and capital gains tax on growth. The annual ISA allowance for 2025/26 is £20,000 per person. Interest earned inside an ISA is completely tax-free — now and in the future.
| ISA Type | 2025/26 Allowance | Key Feature | Who For |
|---|---|---|---|
| Cash ISA | £20,000 | Tax-free interest on cash savings | Everyone 18+ |
| Stocks & Shares ISA | £20,000 | Tax-free growth & dividends on investments | Everyone 18+ |
| Lifetime ISA (LISA) | £4,000 (within £20k) | 25% government bonus (max £1,000/yr) | 18–39, first home or retirement |
| Innovative Finance ISA | £20,000 | P2P lending, tax-free interest | Everyone 18+ |
| Junior ISA | £9,000 | Tax-free savings for under-18s | Under 18 |
Basic rate taxpayers: £1,000 of savings interest tax-free · Higher rate taxpayers: £500 · Additional rate taxpayers: £0. Interest beyond these limits is taxed at your marginal income tax rate.
The Lifetime ISA — the 25% bonus explained
The LISA is one of the most powerful savings tools available to under-40s in the UK. You can save up to £4,000 per year and the government adds a 25% bonus — up to £1,000 per year — on top. The money can only be used for either a first home purchase (property up to £450,000) or retirement (from age 60).
If you withdraw for any other reason, you pay a 25% withdrawal penalty — which effectively claws back the government bonus and takes a small amount of your own savings too. So the LISA should only be used if you’re confident you’ll use it for its intended purposes.
For a first-time buyer saving toward a deposit, a LISA is typically more valuable than a cash ISA on the same money, as the 25% bonus significantly accelerates growth toward the deposit target.
Cash ISA vs Stocks & Shares ISA
A Cash ISA pays a fixed or variable interest rate on your balance, similar to a savings account but with tax-free interest. They are low risk and suitable for shorter-term goals (1–5 years) or an emergency fund.
A Stocks & Shares ISA invests your money in the stock market. Returns are not guaranteed and your capital can fall in value, but historically equity returns over long periods (10+ years) significantly outperform cash savings. For money you won’t need for 10 or more years, a Stocks & Shares ISA is typically the better long-term vehicle.
The key rule: if you’ll need the money within 5 years, use cash. If it’s 10+ years away, use equities.