In addition to knowing
1. What bills to pay
2. How to pay them
3. Where all the accounts are
4. All passwords
spouses/partners need to make sure they will have access to the accounts if one of them dies. My Mom paid all the bills, but Dad knew about all their finances and how much was in each account. Even though both their names were on every account, Mom got locked out of several of them after Dad died.
What do you mean by "locked out"? Do you mean she couldn't access them at all? For how long?
Were the joint accounts labeled 'and' as in Mary and
John Smith, or were they labeled 'or' as in Mary or
It's probably a good idea to have at least one account in only one person's name with the other as beneficiary, but I still find the concept of not being able to access ones own account very puzzling and a bit scary.