The ISA (Individual Savings Account) is the UK's most valuable tax wrapper for ordinary savers and investors. Everything inside an ISA grows free of UK income tax and capital gains tax, and you don't need to declare it on your Self Assessment.
The 2025/26 £20,000 allowance
You can put up to £20,000 into ISAs per tax year (6 April – 5 April). The allowance is use-it-or-lose-it — unused allowance doesn't carry forward. You can split it across as many ISA types as you like, with one exception: Lifetime ISA contributions count inside the £20k and are capped at £4,000 per year.
The four types of ISA
Cash ISA — like a savings account, no market risk. Interest is completely tax-free. Good for short-term savings (emergency fund, near-term purchases). Fixed-rate or easy-access variants available.
Stocks & Shares ISA — invest in funds, ETFs, individual shares, bonds. All gains and dividends are tax-free. Best for long-term savings (5+ years) where short-term volatility doesn't matter.
Lifetime ISA (LISA) — for first home (up to £450,000 purchase price) or retirement (from 60). Government adds 25% bonus on contributions. Early withdrawal for any other reason incurs a 25% penalty — effectively reclaiming the bonus and some of your own money.
Innovative Finance ISA — peer-to-peer lending wrapper. Higher risk than Cash, without the FSCS protection. Has cooled significantly since P2P lender collapses — not recommended for most people.
Transfers between ISAs
Moving money between ISAs (e.g. from Cash to Stocks & Shares) does NOT use your annual allowance — but you must do it via a provider-to-provider transfer, not by withdrawing and re-depositing.
- Transfers of current-year contributions must move the entire current-year subscription.
- Transfers of prior-year ISA money can be partial or full.
- From April 2024, you can subscribe to multiple ISAs of the same type in one tax year — previously limited to one of each type.
Lifetime ISA — the gotchas
The LISA is very generous but has sharp edges:
- £450,000 property price cap — a real problem in parts of the South East where "first home" often costs more. Property prices rising; cap hasn't moved since 2017.
- 12-month wait — the bonus only becomes available after 12 months of opening the LISA. Open it before you need it.
- 25% penalty on early withdrawal — this isn't 25% of the bonus, it's 25% of the whole withdrawal. Put in £4,000, get £1,000 bonus (= £5,000), withdraw it early for a non-qualifying reason, pay £1,250 penalty = you get £3,750 back. You LOSE money.
- Cut-off age 50 — no contributions (or bonus) after your 50th birthday.
Simple ISA strategy
For most people, the right answer is:
- Fill your emergency fund (3–6 months of expenses) in a Cash ISA.
- If you're saving for a first home within ~5 years and your target is under £450k, max the LISA for the 25% bonus.
- Put remaining savings in a Stocks & Shares ISA in low-cost global equity funds for long-term growth.
- Don't use the Innovative Finance ISA unless you fully understand P2P lending risk.