How Does the Annual ISA Allowance Work?

In the 2026-27 tax year, which runs from 6 April to 5 April, the ISA allowance is £20,000: the most an adult can pay into all of their ISAs combined, not per ISA type. gov.uk says you can save up to that amount in one account or split the allowance across multiple accounts. gov.uk describes no carry forward of unused allowance, so this guide does not assume that an unused part is added to a later year.

The site's rules data was last checked against gov.uk on 26 September 2026. Figures typed in this guide may not yet reflect a later change, and the descriptions of gov.uk pages are summaries that may also lag. The current figures are on the ISA rules at a glance page. General information only, not financial advice.

How much is the ISA allowance?

The GOV.UK page on how ISAs work says that every tax year you can save up to £20,000 in one account or split the allowance across multiple accounts, and that the tax year runs from 6 April to 5 April. It is a total limit across all of your ISAs combined, not £20,000 per ISA type. The Lifetime ISA and the Junior ISA have their own limits within this framework:

• Lifetime ISA: you can pay up to £4,000 a year into one, which counts towards the overall £20,000, and the government adds a 25% bonus (GOV.UK: Lifetime ISA).
• Junior ISA: a limit of £9,000 for children under 18, which is set separately from the adult limit (GOV.UK: Junior ISAs).

An HMRC newsletter says the ISA annual subscription limit will remain at £20,000 until April 2031 (HMRC tax-free savings newsletter 19).

What is changing for cash ISAs?

Regulations made on 10 September 2026 (SI 2026/1018, regulation 6, read on legislation.gov.uk on 6 October 2026) set a separate yearly limit on how much savers who are under 65 at the end of the tax year can pay into cash ISAs, lower than the overall allowance, to apply from April 2027. The GOV.UK policy paper says the overall ISA limit is retained and that the cash ISA limit for those aged 65 or over is not reduced (GOV.UK: cash ISA limit reduction). The change is made in law and is not yet in force. The Cash ISA Calculator page sets out the current limits and dates. The guide to the cash ISA changes from April 2027 explains what is changing and who is affected. For the current limits and dates in one place, see ISA rules at a glance.

Who can use the ISA allowance?

gov.uk says you must be 18 or over to open an ISA, and must be resident in the UK (or fall into one of the other groups it lists). It also says you cannot hold an ISA with someone else (GOV.UK: Individual Savings Accounts). The allowance is therefore a limit for each person, not for each household.

Can the allowance be split across ISA types?

Yes. The allowance can be divided across a Cash ISA, a Stocks and Shares ISA, an Innovative Finance ISA and a Lifetime ISA (up to its £4,000 cap), as long as the total does not go above £20,000 in the tax year. gov.uk gives an example of saving in one cash ISA, in another cash ISA and in a stocks and shares ISA in the same tax year. The only type where a second account is not allowed is the Lifetime ISA: gov.uk says you can only pay into one Lifetime ISA in a tax year.

Worked example. These are assumed amounts, not suggestions.

• £8,000 into one Cash ISA, £6,000 into another Cash ISA and £6,000 into a Stocks and Shares ISA uses the whole £20,000 allowance.
• £2,400 into a Lifetime ISA leaves the rest of the allowance (£20,000 less £2,400) for other ISAs, because the Lifetime ISA payment counts towards the total.
• £15,000 into a Stocks and Shares ISA and £7,000 into a Cash ISA comes to £22,000, which is £2,000 more than £20,000, so the payments would go over the limit.

The ISA Contribution Split Planner compares how different splits between Cash and Stocks and Shares could work out.

What happens if the full allowance is not used?

gov.uk sets the allowance for each tax year and describes no carry forward, so this guide does not assume that an unused part is added to a later year. Each new tax year the allowance is set again, whatever was used previously. The ISA Allowance Checker shows how much would need to be paid in each month to use the allowance in full, and how much of it has been used so far.

How do withdrawals affect the allowance?

gov.uk says you can take money out of an ISA at any time without losing any tax benefits. Whether money taken out can be paid back in without using more allowance depends on the ISA. If your ISA is flexible, you can take out cash and put it back in during the same tax year without reducing your current year's allowance. If it is not flexible, only the unused allowance can be paid in (GOV.UK: withdrawing your money).

What allowance mistakes are common?

• Paying into more than one Lifetime ISA in the same tax year. Several Cash or Stocks and Shares ISAs can be paid into in one tax year, but only one Lifetime ISA.
• Withdrawing money and paying it into a different ISA instead of using the transfer process. gov.uk says that if you withdraw the money without using it, you will not be able to reinvest that part of your tax-free allowance again (GOV.UK: transferring your ISA).
• Treating the Lifetime ISA as a separate allowance. It counts towards the overall £20,000, not in addition to it.
• Leaving payments until close to 5 April. The pages read do not say how a provider treats a payment that arrives after the tax year ends, so the provider's own cut-off is the point to ask about.

What to check about the allowance

• How much has been paid into all ISAs so far this tax year, including any Lifetime ISA?
• Does the ISA offer flexible withdrawals, which affect whether money taken out can be replaced?
• Is regular monthly paying in more convenient than a single lump sum near the end of the tax year? That is a question of preference, not a rule.
• Do goals, risk tolerance or interest rates mean the split between ISA types needs reviewing?

The ISA Calculator shows how paying in regularly could grow at an assumed rate, and the Advanced ISA Planner compares different contribution approaches. Their results are illustrations, not forecasts.

Frequently asked questions

Does the ISA allowance carry over to the next tax year?

The tax year ends on 5 April. gov.uk sets the allowance for each tax year and describes no carry forward, so this guide does not assume that an unused part is added to a later year.

Does the Lifetime ISA have its own separate allowance?

No. The Lifetime ISA's £4,000 annual limit counts towards your overall £20,000 ISA allowance, not in addition to it.

When does the ISA tax year start and end?

gov.uk says the tax year runs from 6 April to 5 April. The current tax year is 2026-27.

Will the ISA allowance change?

An HMRC newsletter says the ISA annual subscription limit will remain at £20,000 until April 2031. A separate, lower limit on cash ISA payments is due to apply to savers under 65 from April 2027, while the overall allowance stays the same.

---

This guide does not constitute financial advice. Your personal situation, tax position, and savings goals may mean different strategies are appropriate. Consider speaking to a regulated financial adviser if you are uncertain.