Is a Secret Bank Account in Marriage Sinful?

Generally, it would be morally wrong for one of a married couple to have a secret income, since marriage includes a common life. But in some difficult or extreme situation where it is necessary to protect one of the spouses’ interests, or that of their children, it would be permissible. Say, one of the spouses is a drug addict and is spending the income needed for legitimate support; in this case, it would be permissible to hide funds from the troubled spouse. Or if one spouse was simply improvident and imprudent with investments or purchases to the point of risking the family’s well being, then one could have secret account, or another source of money from family or friends. Of course, this should not be done impulsively, but with some counsel from prudent persons, perhaps even legal counsel.