posted 4th November 2026
If you live in the UK, you have almost certainly heard the word “ISA”. Banks mention it, newspapers write about it, and every spring there is a wave of adverts about using your allowance before the tax year ends. But if nobody has ever explained what an ISA actually is, it can all sound like jargon.
This article is a general introduction. It explains what an ISA is, the main types, the basic rules and what is changing. It is educational information only. It does not recommend any product, provider or course of action.
What is an ISA?
ISA stands for Individual Savings Account. It is not a single product. It is a tax wrapper: a set of rules from HMRC that lets certain savings and investments grow without being taxed.
Inside an ISA, you do not pay:
• income tax on interest,
• tax on dividends,
• capital gains tax on profits.
An ISA does not increase your returns by itself. What you earn depends on what is held inside it, such as a savings account or a set of investments. The wrapper only affects the tax you pay on any gains.
The basic rules
• Annual allowance: for 2026/27, the total you can pay into your adult ISAs is £20,000. This is a single combined limit across all your ISAs.
• Tax year: it runs from 6 April to 5 April. Unused allowance does not carry over.
• Who can open one: you generally need to be a UK resident. You usually need to be 18 or over, although Cash ISAs are available from age 16.
• Several accounts: you can pay into more than one ISA of the same type in the same tax year, as long as the total stays within the limit.
• Moving providers: you can transfer an ISA to another provider and keep its tax-free status, but you must use the official transfer process.
Withdrawing the money and paying it in elsewhere would use up new allowance.
The main types of ISA
Cash ISA.- A savings account in which the interest is tax-free. Cash held with UK-authorised banks and building societies is covered by the Financial Services Compensation Scheme (FSCS), up to the official limit. Interest rates vary and may change over time. Over long periods, inflation can reduce what your money can buy.
Stocks and Shares ISA. - Holds investments such as funds, shares and bonds. Gains and dividends are tax-free, but the value of investments can go down as well as up, and you can get back less than you put in. It is not covered by the FSCS against investment losses.
Lifetime ISA (LISA). - Available to people aged 18 to 39 when they open it. You can pay in up to £4,000 a year, and the government adds a 25% bonus, up to £1,000 a year. The money can be used towards a first home (up to £450,000) or taken from age 60. Withdrawing for other reasons usually brings a 25% charge, which can mean getting back less than you paid in.
Innovative Finance ISA. Holds peer-to-peer loans and similar products. These are higher-risk and generally are not covered by the FSCS if a borrower defaults.
Junior ISA. - For under-18s, with a separate limit of £9,000 a year. The money belongs to the child and becomes theirs at 18.
Are the rules changing?
Yes. In the Autumn 2025 Budget, the government announced a change to Cash ISAs, taking effect from 6 April 2027:
2026/27 From 6 April 2027
Overall ISA limit £20,000 £20,000
Cash ISA limit, under 65 £20,000 £12,000
Cash ISA limit, 65 and over £20,000 £20,000
The overall limit stays at £20,000. The change affects how much of that total can go into a Cash ISA for people under 65. Money already held in a Cash ISA is not affected. How the rule applies to people who turn 65 during the 2027/28 tax year was due to be clarified after consultation, so it is worth checking the final rules on gov.uk.
There is also a separate announcement about the Lifetime ISA. The government plans to replace it with a new ISA aimed only at first-time buyers, expected around April 2028, following a consultation that opened in June 2026. Existing Lifetime ISA holders will be able to keep paying in. The final details have not been confirmed.
Why do people look at ISAs?
The tax-free treatment is the main reason. The tax-free allowances outside ISAs (for interest, dividends and capital gains) have been reduced in recent years, so more people may find that some of their savings or investment income is taxable.
Other reasons people mention include:
• ISA income does not need to be reported on a Self Assessment return.
• Withdrawals from most ISAs are tax-free and do not count as taxable income.
• You can usually access the money without penalty (the Lifetime ISA is the main exception).
Things to be aware of
An ISA is not right or wrong for everyone, and it has limitations:
• The allowance is use-it-or-lose-it. You cannot carry it forward.
• There is no tax relief on what you pay in, unlike with pensions.
• Investment risk. In a Stocks and Shares ISA, values fluctuate and there are no guarantees.
• Cash and inflation. Interest rates may not keep pace with rising prices.
• Charges. Platform and fund charges can reduce returns, and they matter more over long periods.
• Rules can change. Allowances and conditions are set by the government and may be updated.
• Tax benefits depend on your circumstances. If you are unlikely to pay tax on your savings anyway, the benefit may be smaller.
Common misunderstandings
1. “An ISA is an investment.” It is a wrapper. What is inside it decides the risk and return.
2. “The limit applies to the balance.” It applies to what you pay in during the tax year, not what the account is worth.
3. “I can only have one ISA.” You can hold several, within the combined allowance.
4. “Moving an ISA means withdrawing it.” Using the official transfer process keeps the tax-free status.
Want to go deeper? Read our full lesson
This article only covers the basics. We have prepared a dedicated lesson on ISAs with much more detail, including a closer look at each ISA type, how costs and charges work, how the April 2027 change fits in, and how people at different stages of life, such as in their twenties or in their fifties and beyond, may think about the topic.
*You can find it on our website: https://www.tailoredinvestments.co.uk/courses-available*
The lesson is educational and general. It is not personal advice, and it does not recommend any specific product or provider.
Useful official sources
• gov.uk, “Individual Savings Accounts (ISAs)”
• MoneyHelper, free and impartial money guidance
• FSCS (fscs.org.uk), for protection of deposits and investments
• FCA Register (register.fca.org.uk), to check whether a firm is authorised
This article is provided for general information and education only. It is not financial, tax or investment advice, and it is not a recommendation or an invitation to buy, sell or open any financial product. Tax treatment depends on individual circumstances and may change in future. The value of investments can fall as well as rise, and you may get back less than you invest. If you are unsure what is right for you, speak to a financial adviser authorised by the Financial Conduct Authority.