Overview
Several ISA apps can each show room to pay in, while none knows exactly what you contributed elsewhere. That makes an accidental overpayment possible even when every individual account accepted the money.
Before taking money back out, establish whether you actually exceeded the limit. Existing ISA transfers, growth and new subscriptions do not all count in the same way.
Quick Answer
For 2026/27, the overall adult ISA subscription allowance is £20,000. If fresh contributions across your adult ISAs exceed it, stop further payments and contact the relevant provider.
HMRC's current guidance allows providers to correct current-tax-year oversubscriptions by removing excess subscriptions and related gains. Previous-year errors follow HMRC's process. Do not assume an ordinary withdrawal repairs the tax record.
Reconcile Contributions, Not Account Balances
Make a list covering the tax year from 6 April to the following 5 April.
| Transaction | What to establish |
|---|---|
| New payment from your bank account | Normally a fresh subscription |
| Formal transfer of existing ISA money | Normally not a new use of the annual allowance |
| Interest or investment growth inside the ISA | Not a fresh contribution from you |
| Flexible withdrawal and replacement | Check the account's rules and replacement entitlement |
| Lifetime ISA contribution | Counts within the adult overall allowance and its own limit |
The ISA allowance guide covers the main rules. Use provider statements rather than reconstructing everything from memory.
A Worked Overpayment Example
Assume you paid £12,000 into a cash ISA, £6,500 into a stocks and shares ISA and £2,000 into a Lifetime ISA during 2026/27. Total new subscriptions are £20,500.
On those simplified facts, the apparent overall excess is £500. A separate £30,000 transfer from an older ISA does not turn the excess into £30,500.
Now suppose one of the payments was a valid flexible replacement. The calculation may change. Give the provider the withdrawal and replacement details rather than deciding that every incoming transaction counts identically.
Do not deduct a normal withdrawal from subscriptions unless the applicable rules support that treatment.
Opening Two ISAs Is Not the Same Error
For current adult cash ISA rules, opening or paying into more than one account is not automatically the problem. The overall limit, product-specific restrictions and your eligibility matter.
If your concern is simply that you used two cash ISAs, read accidentally paid into two cash ISAs before asking for an account to be closed.
Lifetime ISAs and Junior ISAs have additional restrictions. Do not apply an adult cash ISA explanation to every wrapper.
Current-Year Error: Contact the Provider
Tell the provider the tax year, dates, amounts and other subscriptions that created the apparent excess. Ask whether it can make a formal repair under HMRC's current guidance.
The repair can involve related income or gains, so the amount removed may not be exactly the amount you first calculated. Investment values can also have changed.
Ask for written confirmation showing what was corrected and how the subscription record now stands. Keep it with the other providers' statements.
Do not instruct several providers to remove the same excess independently. Make clear what each has already done.
Previous-Year Error: Keep the Years Separate
An oversubscription discovered after the tax year ended needs to be identified as a previous-year problem. HMRC's guidance tells providers that HMRC will contact the investor in due course for such errors.
Ask the provider and HMRC what action is appropriate rather than moving funds based on a current-year example. Record the discovery and your enquiry.
A withdrawal in the new year does not, by itself, rewrite the previous year's subscriptions. It can instead create an additional transaction whose treatment needs explaining.
Avoid Making the Position Harder to Unpick
Pause standing orders or scheduled ISA top-ups while you reconcile the figures. Keep the money available elsewhere if you are waiting for instructions.
Do not transfer the affected ISA repeatedly, sell investments unnecessarily or close an account purely to make the app balance look correct.
Our flexible ISA guide explains why flexibility is a specific account feature, not a general permission to undo any overpayment.
Rules After This Tax Year
This article's £20,000 example concerns the overall adult allowance in 2026/27. Cash ISA subscription rules change from April 2027, including an age-dependent cash limit, so do not reuse the example for a later year's cash-only calculation without checking the updated rules.
Existing balances and valid transfers are distinct from new subscriptions. Keep that separation in your annual records.
Frequently Asked Questions
Explore savings guides. This is general information; ask HMRC or a qualified adviser about a complex or disputed tax position.
