My parent added me as a joint owner of their checking account so I can write checks for them. What happens to the account if my parent dies before me?

On the death of your parent, you automatically become the owner of the balance of the funds in the checking account regardless of what your parent’s Will says or what their intentions were, unless others can prove they had other intent at the time you became a joint owner. Pennsylvania considers this a transfer of 50% of the balance of the account from your parent to you and imposes inheritance tax on the transfer.