ISA rules – have I got this right?

[MajorMantra]

I have a fixed-rate ISA, opened in the 22/23 tax year, which matures in November. At that point it'll have £20k+interest in it.

If I open an easy-access ISA now and pay £20k into it to use my 23/24 allowance, can I then transfer the full balance from the fixed-rate ISA into it come November?

That would mean it would then contain £40k + the original fixed-rate interest + any interest from the new easy-access ISA.

[Mr Pointy]

As long as it is a direct ISA-to-ISA transfer that's fine. Don't go ISA-bank-ISA as that isn't.

[MajorMantra]

Thank you! Given rates have ballooned massively since I opened the fix, I should probably check I'm not losing out by keeping it. Might be worth taking the penalty for early withdrawal...

[MajorMantra]

A further wrinkle... I hadn't realised that ISA terms vary when it comes to transfers in. Was looking at Shawbrook (currently the best rate on MSE) but it appears you can only transfer in when you first open a new ISA, which obviously wouldn't work in the scenario above when I need to wait for the fix to mature.