How the ISA allowance and UK tax year work

Katerina Galkina · EN · 07/10/2026

Track contributions by tax year

For the 2026/27 tax year, the combined adult ISA subscription allowance is £20,000. The UK tax year runs from 6 April to 5 April. GOV.UK explains ↗ that you can divide the allowance between multiple accounts: it is one overall limit, rather than £20,000 at each bank.

Keep a table of contribution dates, providers and amounts. Check the remaining allowance before adding money, particularly when using several apps. Your account balance can exceed the annual allowance because it includes earlier years’ savings and returns. Distinguish the balance from new contributions.

Check whether you can open the account

Adult ISAs normally require you to be at least 18 and meet the GOV.UK residence conditions ↗, with exceptions for certain Crown servants and their spouses or civil partners. There is no joint ISA. Opening an account normally requires a National Insurance number and the provider’s identity checks.

Cash ISAs, stocks and shares ISAs and other types carry different risks. A tax wrapper does not guarantee an investment’s value. Lifetime ISA contributions count towards the overall allowance, with a separate £4,000 contribution limit and specific age, use and withdrawal conditions. Do not choose a LISA solely because a bonus is advertised.

Check withdrawals before replacing money

With a flexible ISA, you can replace withdrawn money in the same tax year without using additional allowance, subject to the account’s rules. A non-flexible ISA does not automatically restore allowance after a withdrawal. Check the withdrawal guidance ↗ and your provider’s terms first.

Record which account is flexible and where replacement funds must go. Check any fixed-term withdrawal penalty. Lifetime ISA withdrawals have separate rules: do not apply ordinary flexible cash ISA assumptions to them.

Use the ISA transfer procedure

To preserve the tax treatment, arrange an ISA transfer through the receiving provider ↗. Withdrawing the money yourself and paying it back is a different process. Check whether the new provider accepts your ISA type, partial transfers and current-year subscriptions, together with fees and any loss of interest.

Keep confirmations from both providers. Do not try to resolve an unclear transfer by making another contribution without checking the position. If you exceed the allowance, contact the provider and HMRC about correcting it rather than assuming a withdrawal cancels the mistake.