What is an ISA?
Your complete guide to tax-free Individual Savings Accounts
Understanding ISAs
An Individual Savings Account (ISA) is a tax-efficient way to save or invest money in the UK. Any interest, income, or capital gains from investments held in an ISA are free from UK income tax and capital gains tax, making them one of the most powerful tools for building wealth.
Types of ISAs
Cash ISA
Tax-free interest on savings. Often used for short-term goals and emergency funds. From 6 April 2027 you can put up to £12,000 a year into cash ISAs if you are under 65. If you are 65 or over, the full £20,000 still applies.
Lifetime ISA (LISA)
For ages 18-39. Save up to £4,000/year with 25% government bonus. Use for first home or retirement after 60.
Innovative Finance ISA
Tax-free investing in peer-to-peer lending and crowdfunding. Higher risk but potentially higher returns.
ISA Rules & Allowances
Annual ISA Allowance
For the 2026/27 tax year, you can save up to £20,000 across all your ISAs. From 6 April 2027, if you are under 65, no more than £12,000 of that can go into cash ISAs, and you will no longer be able to transfer from a stocks and shares ISA into a cash ISA. The £20,000 overall limit is fixed until April 2031.
What is an ISA fee?
The ISA itself is just a tax wrapper. The government does not charge you to hold one. Any fee comes from the provider and depends on what sits inside the wrapper.
Cash ISAs usually have no account fee. Your return is the interest rate, so the "cost" is the gap between your rate and the best rate you could get. The thing to check is the access terms. Fixed-rate cash ISAs often charge an early access penalty, usually a number of days' interest, if you take money out or transfer before the term ends.
Stocks and shares ISAs usually have up to four costs. First, a platform or account fee, charged either as a percentage of your pot each year or as a flat monthly amount. Second, the ongoing charge (OCF) on each fund you hold, which comes out of the fund's value rather than appearing as a bill. Third, dealing fees each time you buy or sell shares, investment trusts or ETFs. Fourth, foreign exchange (FX) fees when you buy investments priced in another currency.
Worked example, using illustrative figures rather than any particular provider. You hold £20,000 in a stocks and shares ISA. A 0.25% platform fee costs £50 a year. A flat £5 a month fee costs £60 a year. At £20,000 the percentage fee is cheaper. At £30,000 the same 0.25% costs £75, and the flat fee is cheaper. The crossover is £24,000. Add a fund with a 0.20% ongoing charge (£40 a year on £20,000) and your yearly cost is about £90 to £100 before you trade at all.
That is why a fee that looks small can matter. On a £20,000 pot, 0.5% a year more in charges is £100 a year, every year, and it compounds with the pot.
Compare platforms' published charges side by side in our guide to UK investment platforms and their fees, and see how the Lifetime ISA differs in Lifetime ISA fees and interest rates.
Choosing the Right ISA
Consider a Cash ISA If:
- ✓You're saving for short-term goals (1-3 years)
- ✓You do not want the value to go down (interest rates can still change)
- ✓You're building an emergency fund
- ✓You're new to saving and investing
Consider a Stocks & Shares ISA If:
- You're investing for the long term (5+ years)
- You're comfortable with investment risk
- You want potentially higher returns
- You're saving for retirement or long-term goals
ISA Strategy Tips
Use Your Full Allowance
Try to use your full ISA allowance each year if possible. Even small amounts compound significantly over time due to tax-free growth.
Start Early
The earlier you start using ISAs, the more time your investments have to grow tax-free. Even small regular contributions can build substantial wealth over time.
Diversify Within Your ISA
If using a stocks & shares ISA, spread your investments across different asset classes and sectors to manage risk effectively.
Review Regularly
Review your ISA investments annually to ensure they still align with your goals and risk tolerance.
ISA vs Other Tax-Efficient Options
| Feature | ISA | SIPP | General Investment |
|---|---|---|---|
| Tax Treatment | No income tax or CGT | Tax relief on contributions, no CGT | Subject to income tax and CGT |
| Access Age | Any age (except LISA restrictions) | 55 (rising to 57 in 2028) | Any age |
| Annual Limit | £20,000 | £60,000 (or 100% of earnings) | No limit |
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