Proposals to equalize the tax treatment of married couples were floated in 1933, 1934, 1937 and 1941, but none of the proposals were adopted.
The closest Congress came to making changes to the tax system came in 1941, when the House Ways and Means Committee proposed a mandatory joint return, with married couples being taxed on their combined income without the option to file separate returns or and without the option of applying community property laws.
This would have resulted in a tax increase on all two-income married couples. As Boris Bittker explains:
(T)wo unmarried taxpayers with separate sources of income would have to pay a heavier tax if they got married than if they lived together without benefit of clergy, and many married couples would be able to reduce their tax burden by getting divorced. Quite naturally, therefore, opponents of the proposal assailed it as “a tax on morality.”
The proposal was never enacted, so the inequality between common law and community property states continued through World War II.
Some common-law states began taking matters into their own hands.
Oklahoma led the way, enacting community property provisions in 1939. Hawaii, Michigan, Nebraska, Oregon and Pennsylvania would follow Oklahoma’s lead. Proposals to enact community property law were also debated in Massachusetts and New York, but were never passed.
Finally in 1948, Congress acted. For the first time, filing statuses were created and we moved closer to the tax system we know today.