Shacking Up or Shelling Out: Income Taxes,Marriage, and Cohabitation

Anecdotal evidence suggests that the income tax penalty associated with marriage contributes to the decision of a couple to live together as a married vs. a cohabiting couple. In this paper, we use household data from the Panel Study on Income Dynamics to estimate the impact of various factors, including the federal individual income tax, on a couple's decision to marry instead of cohabit. We find that the initial decision to form either a cohabiting or a married union is only marginally affected by the income tax consequences of one form of union vs. another, and other factors play a more important role. However, for those already living together as a cohabiting couple, the decision to make the transition from a cohabiting to a married couple is significantly affected by the tax consequences of such a move. Here, an increase in the income tax at legal marriage, or an increase in the marginal tax rate with marriage, has a statistically significant and negative impact on the probability of transition from cohabitation to legal marriage. However, the magnitude of the tax impact is generally small, and several other variables are more important determinants.