Anyone with a Cash ISA is being urged to use up their tax-free deposit allowance before Sunday at midnight.

The 2025-26 Cash ISA deposit limit of £20,000 will be closed from one minute after 11.59pm on Sunday, April 5. It means that anyone who fails to maximise the full £20,000 limit will not be able to top it up any more from Monday, April 6, and instead will be forced to use their 2026-27 deposit limit for the next tax year instead.

But at this crucial changeover point, savers can maximise both sets of deposit limits within two days, thus saving a maximum of £40,000 into a Cash ISA between Sunday and Monday.

Money expert Martin Lewis last year explained how you could add £40,000 to a Cash ISA between one tax year and the next tax year, and then more money on top next April .

Now, before Monday, April 6 2026: Add up to £20,000 to Cash ISA.

Between Monday, April 6 2026 and April 6 2027: Add another £20,000 to Cash ISA

After April 6 2027: Add £12,000 to Cash ISA under the new limits for 2027-28.

It means that savers are free to stash up to £20,000 into their tax-free Cash ISA by April 5, as long as they haven’t already maxed out their allowance in existing ISAs so far this tax year.

They will then also have another £20,000 allowance open to them from Monday, April 6, 2025 until April 5, 2026.

In this way, you could deposit £40,000 tax-free into a Cash ISA in just two days.

Speaking on an episode of The Martin Lewis Podcast on March 19, Martin said: “The ISA deadline is April 5, that’s when the ISA year closes, because it’s the end of the tax year and you have an ISA allowance, a savings or investing allowance, that you can use each year.

“And if you do not use it, you lose it.”