Married couples can choose to file US federal taxes separately or jointly. The liability of most couples depends on whether they are married or not. This dependence could be removed by having each person pay tax only on her or his own income, with no possibility of joint returns for married couples. If this reform were implemented without any other change in the federal tax law,

		most married couples who file jointly now would be able to pay less tax.
		most married couples who file jointly now would have to pay more tax.
		married couples who file jointly now would have no change in their total tax liability.
		it would give couples a money incentive to get married before the new law went into effect.
		it would give married couples a money incentive to divorce before the new law went into effect.