Law /
Paying tax on UK I.S.A. in Poland? [20]
If you cash in your ISA then you would need to pay Polish tax on the benefits, assuming you meet the Polish residency test.
If you dont cash it in and only have paper gains then you are OK and have no tax to pay.
the ISA follows residency not citizenship and thus I think you are barred from making new contributions to the ISA while you are not tax resident in Britain.
You should check all of the above however - i had the same experience when leaving from a work tour in Britain. Its now very difficult for US citizens to open a new ISA even if they are long term residents of Britain.
all that said for the amounts involved I dont think it would be worth engaging an accountant - just ring up the people managing your ISA and ask them.