Till taxes do us part: Tax penalties or bonuses and the marriage decision

The tax regimes applied to couples in many countries including the US, France, and Germany imply either a marriage penalty or a marriage bonus. We study how they affect the decision to get married by considering two potential spouses who play a marriage proposal game. At the end of the game they may get married, live together without formal marriage, or split up. Proposing (or getting married) implies a cost that can indicate strong love. The striking property we obtain is that a marriage bonus may actually reduce the probability that a couple gets married. If the bonus is sufficiently large, signaling is no longer informative, and a pooling equilibrium in which no couples get married remains. Similarly, a marriage penalty may increase marriages. The penalty may lead to a separating equilibrium with efficiency enhancing information transmission, which was otherwise not possible.