If tou are asking whether any back tax charge would be levied, the answer is no, provided the ISA rules were followed. FUTURE interest will be taxable if you transfer out of the ISA but as Giz says you have an allowance.
If the ISA was in joint names you may find you both get the £85000 protection- it is per person as I understand it- so as long as it's listed under 2 names you should both be covered.