Answer
Wa `alaykum as-Salamu wa rahmatullahi wa barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
The joint account of your father and mother is owned by both of them. Should either of them pass away, half of the account may be considered the deceased’s estate and should be distributed among all the heirs.
In his response to your question, Prof. Dr. Monzer Kahf, Professor of Islamic Finance and Economics at Qatar Faculty of Islamic Studies, states:
The principle you mentioned regarding expenses is correct. Family expenses are the sole responsibility of the husband/father. The wife is not responsible to contribute to the family expenses.
However, the joint account is a different matter.
Joint accounts usually mean that while the two persons who own the account are alive they own its balance on equal shares but when one of them dies the other becomes the owner of all the funds.
This is the usual way that joint accounts are defined in most civil and commercial laws throughout the world including most, if not all, Arab countries.
On the other hand, the Shari`ah does not accept that the surviving joint account holder becomes the sole owner and that the account continues on half/half basis even after the death of one of them.
We consider the fact that one spouse puts her/his property in a joint account is an indication that that spouse intends to give one half ownership of that property as a gift to the other. Gifts between spouses are permissible and have no limits whatsoever.
Now, this means that your mother, unless it can be proven otherwise, by putting her income in a joint account, is giving half of it to your father. The same applies to your father.
Hence, if one of them dies, then the balance in this joint account is considered to be owned half/half and the half that belongs to the deceased must be distributed according to the rules of inheritance, in which the other spouse will have a share.
Of course, a property that is not in a joint account will be distributed directly according to the rules of inheritance.
Read also:
Can a Husband Take His Wife’s Salary by Force?
Can Husband Prevent Wife From Working?
Should a Husband Give His Wife Spending Money?
Can a Husband Force His Wife to Work in Islam?
Almighty Allah knows best.