What happens if you break the ISA rules

When an ISA breaks the rules it is either repaired or voided. A repair removes only the excess subscription and the income on it, so the rest of the account stays tax free; a void removes the whole invalid subscription and all its income. Either way, the income and gains on the money taken out lose their ISA exemption and are taxed like any other savings or investment income.

What counts as breaking the ISA rules?

HMRC’s guidance for ISA managers, How to close, void or repair an ISA, calls an account that breaks the rules an invalid ISA. It gives three broad examples: the account holds investments that do not qualify, the investor is not a qualifying individual, or a subscription to the account is invalid.

In practice the usual problems are:

• Paying in more than the overall limit. For 2026 to 2027 the most you can save across all your ISAs is £20,000, and no more than £4,000 of that can go into a Lifetime ISA.
• Withdrawing and paying back into a non flexible ISA. HMRC’s subscription guidance says the limit applies to the amount subscribed and is not reduced by a later withdrawal, so money paid back counts again.
• Self transfers. HMRC says investors cannot move an ISA by closing it and opening a new one, even with the same manager. The money paid into the new account is a fresh subscription.
• Not qualifying to subscribe. You must be 18 or over and resident in the UK, unless you are a Crown servant or the spouse or civil partner of one. Subscriptions made while non resident or under age are invalid.

The basic rules on limits and transfers are covered in our guide to ISA tax rules.

What is the difference between repairing and voiding an ISA?

HMRC’s guidance says invalid accounts can, in certain circumstances, continue as ISAs after being corrected, which is known as a repair. Two kinds of failure can be repaired: an inadvertent failure in the checks the manager should have carried out (manager error), and an investor exceeding the overall subscription limit (investor error).

Accounts that cannot be repaired must be voided. Subscriptions made while the investor did not meet the residence condition, or was under age, cannot be repaired; the manager must void them. Voiding removes the invalid subscription and all income earned on it. HMRC is clear that valid subscriptions in earlier and later tax years are not affected. The exception is an ISA opened under a continuous application: there, all subscriptions in the tax year of the breach, and any gains, must be removed.

Voiding a stocks and shares or innovative finance ISA does not force a sale. If the terms allow, the manager can transfer the investments to the investor to hold outside the ISA. A life insurance policy in a voided ISA must be terminated instead.

How is an over subscription fixed in the same tax year?

If the investor tells the manager they have gone over the limit in the current year, the manager can remove the excess and any related gains, following the investor’s instructions on which subscriptions to take out. The valid current year subscriptions keep their exemption.

Managers must design their systems so that no more than the overall limit can be paid into the ISAs they run for one investor. Where merged systems cannot talk to each other, HMRC lets managers run cross checks, and if a check within 60 days of the over subscription finds one, the manager removes it without contacting HMRC. Managers do not have to find out what you pay into ISAs held elsewhere: HMRC says investors who use several managers are responsible for keeping within the limit.

What happens if HMRC finds it in a later year?

ISA managers send HMRC a return of information within 60 days of 5 April each year, so by 4 June, listing every ISA and its subscriptions. HMRC matches these returns and can spot an investor who has gone over the limit across several providers.

For earlier years the manager must not act on its own. HMRC may write to the investor first, giving them the chance to query the figures. If an ISA needs repairing, HMRC issues a notice of discovery to the manager and tells the investor what will happen. The date of that notice is the date of repair. Within 30 days of it, the manager must identify the investments bought with the excess, remove them and remove the income on them.

All income tax and capital gains tax relief on the excess is lost from the date of the first invalid subscription up to the date of repair. After the excess is removed, the balance carries on as a valid ISA. Identification of which investments to remove can be done by taking a fraction of the holdings or by tracing subscriptions through the account, but that choice applies only for ISA purposes; normal capital gains identification rules still govern disposals.

How is tax on the income collected?

Since 6 April 2016 ISA managers have not deducted tax from interest on invalid subscriptions. HMRC’s guidance says that income removed from an ISA counts towards the investor’s Personal Savings Allowance or dividend allowance, and capital gains tax applies to gains on disposals of the removed assets. The manager must tell you there may be more tax to pay.

The manager must give you the information needed to work out the tax: the dates and amounts of income, any tax deducted, the cost and acquisition date of the investments and, where they have been sold, the disposal date and proceeds. HMRC tells investors to report the income and gains for the tax year in which they arose.

If you complete Self Assessment, that is where it goes. If you do not, GOV.UK explains that tax on taxable interest is usually collected through your tax code or by a Simple Assessment letter; see savings interest in your tax code. Where the manager had reclaimed tax from HMRC on income from the invalid investments, it must repay it, normally by deducting it from its next tax claim.

Are Lifetime ISAs treated differently?

Yes, in three ways. First, the manager must contact HMRC for every Lifetime ISA repair. Second, if you exceed the overall limit but not the £4,000 Lifetime ISA limit, the excess is removed from your other ISAs in date order, even if you opened the Lifetime ISA later in the year. That protects you from the withdrawal charge.

Third, if you exceed the Lifetime ISA limit itself, the excess must come out of the Lifetime ISA. Because those were never valid subscriptions, they come out without a withdrawal charge, but any government bonus paid on them must be returned to HMRC. Where the account balance cannot cover the bonus, HMRC may assess the investor for the shortfall. See Lifetime ISA bonus and withdrawal charge.

What does a repair look like in practice?

Illustration only. In 2026 to 2027 Tom pays £15,000 into a cash ISA with one bank and later £8,000 into a stocks and shares ISA with a platform. He has subscribed £23,000, which is £3,000 over the limit.

1. If Tom spots this before the year ends, he tells the platform, which removes £3,000 of the subscription and any gains on it on his instructions. The rest of both ISAs stays valid.
2. If nobody notices, the managers’ returns go to HMRC after 5 April. HMRC writes to Tom, then sends the platform a notice of discovery.
3. Within 30 days the platform removes investments representing the £3,000 and the dividends on them. Tom receives the details and reports the dividends and any gain for the year they arose.

Tom does not lose the tax relief on the other £20,000. Only the excess and its income come out.

What mistakes cause ISA problems?

• Assuming a withdrawal frees up allowance. Only a flexible ISA allows you to replace money withdrawn without it counting again.
• Moving money yourself. Always ask the new manager to arrange a transfer; withdrawing and reinvesting is a new subscription.
• Paying in after moving abroad. You can keep an ISA as a non resident but cannot add to it; see UK ISAs after moving abroad.
• Ignoring the HMRC letter. The letter is your chance to correct the figures before the manager is instructed.
• Missing the April 2027 changes. From 6 April 2027 any ISA receiving a subscription needs a National Insurance number or a declaration that the investor is not eligible for one, and the cash ISA limit falls to £12,000 for savers under 65, within the same £20,000 overall limit; see the cash ISA limit from April 2027.

If HMRC opens a check into your return, tax investigation insurance pays your accountant’s fees. Solar Protect cover pays up to £100,000 with no excess; it never pays tax, interest or penalties. Read how our cover works or get a quote.

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Sources

• GOV.UK: Close void or repair an isa if youre an isa manager
• GOV.UK: Individual savings accounts
• GOV.UK: Manage isa subscriptions for your investors
• GOV.UK: Returns of information for isa managers
• GOV.UK: How you pay tax on savings interest
• GOV.UK: Cash individual savings account isa limit reduction
• GOV.UK: If you move abroad

Reviewed by Christine Anderson, Broker, Solar Protect. Last reviewed 24 October 2026. Part of Accountapedia, the Solar Protect guide to UK tax and accounting. This page is general information, not personalised advice.