Open 2 Cash ISA in one tax year

1) In my case, I opened 2 fixed rate Cash ISA in Bank A in the same day accidentally in 2023/2024, buy only deposit GBP20000 in one Fixed rate Cash ISA, how can I do? Can I close the non-deposited one ISA? 2) In 2022/2023, I already opened a Fixed rate Cash ISA in Bank A, and deposit GBP20000. when It to be matured, Bank A said that it will be in a Cash ISA account. Can I transfer the balance to Bank A's existing ISA account which open in 2023/2024? Is it OK? Is it over the GBP20000 allowance? Many thanks!

Hi Wilson929,
As you have only paid into1 there won't be too much of an issue as no interest has been received in the 2nd account, for details on transfer,
please refer toIndividual Savings Accounts (ISAs)
Thank you.

Thanks for your reply. Do I need to close the non-deposited ISA Cash account? or just remain in my bank dashboard? Thank you.

Hi Wilson929,
You would probably need to close it.
Thank you. 

I too have accidentally opened 2 cash ISAs in the same tax year - 2023/24. First for £20,000 was July 2023/24, with bank A where I also have an ordinary account, was July 2023. The second with Bank B was January 2024, also for £20,000 but at the same time I transferred an old (10+ years) cash ISA for £53,251.07. I informed Bank B of situation a few days ago. I was told that the 'new' ISA and the transferred amount had been amalgamated and the whole must all be cancelled, It would be simpler to cancel the July 2023 ISA if that was allowed but the situation is further complicated because it is now 3 months past the end of the tax year concerned.

Hi,
HMRC will contact you in due course to confirm as any interest received in the 2nd account will not have the ISA protection and will form part of your savings allowance and be taxable.
Thankyou.