Joint account in offshore mutual fund

I'm a UK tax residence. If I held an offshore non-reporting mutual fund with someone else who is not tax-resident in the UK and at some point redeemed the mutual fund (i.e closed and disposed it off) into my individual savings bank account which is not jointly held with anyone else. As I understand this is a taxable even and the net gain is to be reported as "Offshore Income Gains" and the amount I need to declare is 50% of the total gain received because the mutual fund account was held as a joint account. Is this correct?

Hi ustulation,

That is correct.

Thank you.