If its a joint bank account it might well be treated as other joint property, such as your home, i.e., you and your wife have an equal joint undivided share, which could become severed on your bankruptcy. Your trustee might argue that you should 1/2 of what was in the account at the time you were adjudged bankrupt. However, if in truth the money was yours & your wife was a joint account holder for convenience then the trustee might lay claim to all of it. Equally, if it was your wife's she could run the same argument.