INNOCENT SPOUSE RULE -- Section 434(c)(1) of the Internal Revenue Code protects an innocent spouse from tax fraud prosecution under certain conditions. This rule mainly protects women who innocently sign returns while married to men who controlled the finances. An innocent spouse can be protected from liability if 1) a joint return was filed, 2) the return contains a "grossly erroneous" error, 3) he or she establishes "lack of knowledge," and 4) it is "inequitable" to impose the tax on him or her. This rule does not protect the spouse from any legitimate tax obligations for which he or she is responsible under joint and several liability.