If the accounts are in separate names, then she does not automatically have a right to access his bank account, unless and only to the extent he had, while still mentally compentent, executed a power of attorney (POA) giving her that right. However, if she has already been declared his guardian, or is later declared his guardian, then she should be able to manage his finances and access his bank account. Since he will need a guardian anyway to make decisions for him, this is something she should do.  The wife should contact her local family and probate (also known as surrogate's) courts--one or the other should deal with guardianships. They can explain to her the process, where and what to file, etc. Or, if funds permit, she should consult with an attorney to help her.