islamic banking

salaams Mufti saheb.
II currently have an Islamic finance cheque account at FNB.Annually in August they pay out profits to the islamic finance account holders.
My questions are :
1) Is the profits received halaal or must it be disposed of?
2) If it is not halaal can one pay ones personal income tax with it?
3) If it can not be used to pay tax how must it be disposed?
Jazaka Allah