The income tax should embody increasing marginal tax rates.
Country A started to allow married couples to file their incomes separately regardless of the sources of income since 2015. Therefore, this system satisfies (a), (b) and (c) of the following conditions:
(a) The income tax should embody increasing marginal tax rates.
(b) The tax system should be marriage neutral, namely two individuals’ tax burdens should not change when they marry.
(c) Families with equal incomes should pay equal taxes.
