A Cash ISA is a tax-efficient account where you pay no UK income tax on the interest earned. While the standard annual deposit limit is £20,000, a Flexible ISA allows you to withdraw money and replace it within the same tax year into this same account without it counting toward that limit.
As of March 31, 2026, the Plum Cash ISA is flexible. This means if you withdraw funds, that specific amount is added back to your Replaceable Allowance.
Example:
If you have already deposited £15,000 of your £20,000 limit and then withdraw £2,000 for an emergency:
Your Remaining Allowance stays at £5,000.
Your Replaceable Amount becomes £2,000.
To Top Up: The next £2,000 you deposit will fill the "Replaceable Amount" first (returning it to £0).
Further Deposits: Any money added after that will then start reducing your remaining £5,000 Annual Allowance.
Important Limitations
Transfers & Closures: If you transfer your ISA to another provider or close the account, you lose the flexibility for those funds. In those cases, we are required to report your initial deposits to HMRC regardless of withdrawals.
Annual Reset: Every April 6th, your allowance resets to £20,000. Any "Replaceable Amount" from the previous year that wasn't paid back is lost.