Tax on a UK ISA

[ajcoxuk]

Following research on the issues around UK Pensions late in 2025 I have read something which leads me to believe I have misunderstood the German Tax implications of holding a UK ISA.

Obviously I need a German Steuerberater who understands UK ISAs - any suggestions?

If I understand the rules correctly now, the calculations could be extremely complex if followed to the letter but simpler if I just look at the gains made per fund per year in the ISA, Would the Finanzamt accept a simplified calculation if it was done in their favour (i.e. by choosing the exchange rate over the year that produces the highest Euro gain?) That might sound crazy, but I feel a detailed calculation is not going to produce a figure much different and would take a lot of time and effort to produce.

While 2025 will be bad due to the large increase in the stock-market, I think previous years are affected too. How far back must I go and how would this be different from making a normal tax return for 2025?

Finally, I have a multi-currency Wise account and with interest rates returning to normal, I am receiving a small interest payment. Does this also need to be declared? The Euro amounts appear to be taxed in Belgium while I think the Sterling amounts are paid untaxed.

With thanks

[PandaMunich]

Would the Finanzamt accept a simplified calculation if it was done in their favour

No.

Finally, I have a multi-currency Wise account and with interest rates returning to normal, I am receiving a small interest payment. Does this also need to be declared?

Yes.