ISA transfers - anyone who's done it - is it cumulative across multiple years?

[Borelis]

Say I have an ISA with Bank A (with the term being 2014-2016) and input the maximum of £20k.

In year 2017, I open a new ISA with Bank B (variable rate, yearly interest), transfer across the bank A ISA (as it has matured) via ISA transfer = 20k (PLUS input another 20k as I still have the allowance right?) = 40k.

In year 2018, can I then transfer the 40k from ISA with Bank B to another ISA with another bank (1.1% interest) and input an extra 20k (the allowance for that year) i.e. get the interest rate e.g. 1.1% applied onto the total of 60k? i.e. get £660 interest that year?

Disclaimer: Obviously I don't have that much cash floating about haha but I'm just trying to understand how the ISA transfer process works in the long term.

Different accounts had different t&cs when I worked in a building society.

www.gov.uk/individual-savings-accounts/transferring-your-isa

It depends if the account you want to transfer it to allows isa transfers. If it does yes.