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ISA Allowance and Rules

Everything you need to know about ISAs — types, limits, and strategies for maximising your tax-free savings.

Whether you're trying to understand what a pension drawdown is, deciding if you should overpay your mortgage, or checking this year's tax allowances — we've written a guide for it. Everything here is free, jargon-free, and written for real people, not finance professionals.

The Annual Allowance

The ISA allowance is £20,000 per tax year (6 April to 5 April). You can split this across different ISA types, but the total must not exceed £20,000. The allowance does not carry forward — if you don’t use it, you lose it.

Types of ISA

Cash ISA

Tax-free savings account. Interest earned is free from income tax. You can hold one Cash ISA per tax year (multiple from different years).

Stocks and Shares ISA

Invest in funds, shares, and bonds with no Capital Gains Tax or income tax on returns. Best suited for goals five or more years away.

Lifetime ISA

For 18–39 year olds saving for a first home or retirement. £4,000 annual sub-limit (counts towards £20,000 total). 25% government bonus on contributions — up to £1,000 per year. 25% penalty on withdrawals for other purposes.

Innovative Finance ISA

Holds peer-to-peer lending investments. Interest and gains are tax-free, but the underlying investments carry higher risk.

Limits at a Glance

ISA Type Annual Limit
Adult ISA (all types combined) £20,000
Lifetime ISA sub-limit £4,000
Junior ISA £9,000

Key Rules

  • You can hold one of each ISA type per tax year.
  • Unused allowance does not carry forward to the next tax year.
  • ISAs are individual — there is no joint ISA. Couples each get £20,000.
  • You must be a UK resident and aged 18 or over (16 for Cash ISAs).

Transferring ISAs

You can transfer ISAs between providers without losing your tax-free status. Current year contributions must be transferred in full; previous years’ contributions can be transferred partially.

Always use the formal ISA transfer process — withdrawing and redepositing uses up your annual allowance.

Flexible ISAs

Some providers offer flexible ISAs. If you withdraw money, you can replace it within the same tax year without it counting towards your annual allowance. Not all providers offer this, so check before withdrawing.