🇬🇧 UK Financial Tools · 2026/27

UK ISA Calculator
model your tax-free growth

Project your ISA value over time — Stocks & Shares, Cash ISA or Lifetime ISA. See tax-free growth with compound interest for 2026/27.

✓ £20,000 annual allowance✓ Stocks & Shares, Cash & LISA✓ Tax-free growth modelled✓ LISA bonus included
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7.0%
20y
Final ISA Value
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Total contributed—
Tax-free growth—
Effective annual return—
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Contributed vs Growth
ContributionsTax-free growth

What is an ISA?

An Individual Savings Account (ISA) is a tax-free savings or investment wrapper available to UK residents. All interest, dividends and capital gains earned inside an ISA are completely free of UK income tax and capital gains tax — forever. You can save up to £20,000 per tax year across all ISA types combined.

Cash ISA vs Stocks & Shares ISA

A Cash ISA works exactly like a savings account, but the interest is tax-free. Best Cash ISA rates in 2026 sit around 4.5–5.0%. A Stocks & Shares ISA invests your money in assets such as shares, bonds and funds. Returns are higher over the long term — the UK stock market has historically returned around 7% annually including dividends — but are not guaranteed and can fall as well as rise. For money you won't need for at least 5 years, a Stocks & Shares ISA typically significantly outperforms cash over time.

What is a Lifetime ISA?

The Lifetime ISA (LISA) allows you to save up to £4,000 per year (which counts towards your £20,000 ISA allowance). The government adds a 25% bonus — up to £1,000 per year. The money can only be withdrawn to buy your first home (up to £450,000) or from age 60 for retirement. Withdrawing for any other reason incurs a 25% government penalty, which claws back more than just the bonus.

ISA Calculator 2026/27

This calculator projects how your ISA grows over time with regular contributions. Choose between Stocks & Shares ISA, Cash ISA or Lifetime ISA to model different scenarios and see the tax-free growth over your investment period.

ISA types and annual allowances 2026/27

ISA Type Annual limit Access Government bonus
Cash ISA £20,000 Flexible None
Stocks & Shares ISA £20,000 Flexible None
Lifetime ISA (LISA) £4,000 First home / age 60 25% (max £1,000/yr)
Innovative Finance ISA £20,000 Varies None

The £20,000 annual allowance applies across all ISA types combined. Unused allowance cannot be carried forward to the next tax year.

Frequently asked questions

You can save up to £20,000 per tax year across all ISA types combined. The Lifetime ISA has a lower limit of £4,000 per year, which counts towards your overall £20,000 allowance.
Yes — from April 2024 you can open and pay into multiple ISAs of the same type in the same tax year. However, your total contributions across all ISAs must not exceed £20,000 per tax year.
With the best Cash ISA rates around 4.5–5.0%, a Cash ISA makes sense for money you need within 1–5 years, or if you are a higher rate taxpayer who has used your Personal Savings Allowance (£500 for higher rate taxpayers). For longer-term savings, a Stocks and Shares ISA typically outperforms cash.
Your ISA becomes a continuing account. Your spouse or civil partner can inherit your ISA allowance through an Additional Permitted Subscription (APS), allowing them to invest an equivalent amount on top of their own allowance, tax-free.
Yes — you can withdraw from a Cash ISA or Stocks and Shares ISA at any time without tax. Flexible ISAs allow you to replace withdrawn funds in the same tax year without it counting against your allowance. The Lifetime ISA has restrictions: withdrawals for anything other than a first home purchase or retirement from age 60 incur a 25% government penalty.