Investment & ISA guide
What is an ISA?
An Individual Savings Account — ISA — is a tax-efficient wrapper for cash or investments. Interest, investment income and capital gains generated inside an ISA are not normally subject to UK Income Tax or Capital Gains Tax.
The basics
An ISA is a tax wrapper, not an investment in itself.
GOV.UK confirms that you do not pay tax on interest earned on cash held in an ISA, or on income and capital gains from investments held within an ISA.
If you complete a tax return, ISA interest, investment income and gains do not normally need to be declared.
A Stocks & Shares ISA can hold different investments with very different levels of risk. The ISA provides the tax treatment; it does not make the underlying investment safe.
ISA types
There are four main adult ISA types.
Cash ISA
Holds cash savings. Interest is sheltered from UK Income Tax within the ISA.
Stocks & Shares ISA
Can hold qualifying investments such as funds, shares, investment trusts and bonds. Values can fall as well as rise.
Innovative Finance ISA
Can hold certain peer-to-peer loans and other qualifying investments. Risks differ from bank deposits and conventional investment funds.
Lifetime ISA
Designed for a first home or later life, with separate age, contribution, bonus and withdrawal rules.
2026/27 allowance
You can subscribe up to £20,000 across ISAs this tax year.
For the 2026/27 tax year, the overall adult ISA subscription limit is £20,000. GOV.UK says the allowance can be used in one account or split across multiple eligible ISAs.
The £4,000 Lifetime ISA subscription limit counts within the overall £20,000 ISA allowance rather than sitting on top of it.
Unused ISA allowance is normally lost at the end of the tax year; it cannot be carried forward into a later year.
Access
Standard ISAs can usually be accessed whenever you need the money.
GOV.UK states that money can generally be withdrawn from an ISA at any time without losing the tax benefits already earned, although individual providers can apply their own terms or charges.
If the ISA is flexible, money withdrawn can be replaced during the same tax year without using additional current-year allowance. If it is not flexible, replacing withdrawn money normally uses allowance again.
Withdrawals outside the permitted circumstances can result in a withdrawal charge, so a Lifetime ISA should not be treated like an ordinary Cash ISA or Stocks & Shares ISA.
Cash or investment?
The right ISA type depends partly on when the money may be needed.
Shorter-term money
Cash may be more appropriate where preserving nominal value and ready access matter more than long-term growth potential.
Longer-term money
Investing can provide greater long-term growth potential, but values can fluctuate and capital is not guaranteed.
Inflation
Cash avoids investment-market volatility but can lose purchasing power if interest does not keep pace with inflation.
Investment risk
A Stocks & Shares ISA can fall in value. The investments selected should match the objective, timeframe and capacity for loss.
Future rule change
Cash ISA rules are due to change from 6 April 2027.
The Government has announced that from 6 April 2027, people under age 65 will have a £12,000 annual Cash ISA subscription limit within the unchanged £20,000 overall ISA limit.
Those aged 65 or over are due to retain a £20,000 Cash ISA limit. The Government has also announced restrictions on transfers from non-cash ISAs into Cash ISAs for people under 65 and new treatment for cash held inside non-cash ISAs.
For 2026/27, the overall ISA allowance remains £20,000 and the announced Cash ISA restriction does not start until 6 April 2027.
Investment & ISA advice
Not sure how ISA savings should fit into the wider plan?
A personal review can consider your time horizon, access needs, tax position, investment risk and how ISAs sit alongside pensions and other savings.
Book a conversationThis guide is for general information only and is not personal financial, investment or tax advice. ISA and tax rules can change. Investments can fall as well as rise and you may get back less than you invest. Content checked against current GOV.UK guidance on 16 September 2026.