The U.S. income tax code encourages marriage for some and discourages marriage for others, but same-sex couples were only recently exposed to these incentives. We estimate marriage responses by exploiting variation in the recognition of same-sex marriages for tax purposes versus earlier papers leveraging smaller changes. Using the American Community Survey, which reports cohabitation and marriage, we estimate a significant though very small marriage elasticity, with further analysis suggesting a higher (though still small) elasticity for low-earning households and in response to federal taxes specifically. Our estimates imply that the 2018 tax reform will increase marriage among high-earning cohabiting couples.

The Social Security earnings test taxes away benefits at a 33%-50% rate once earnings pass a threshold amount. I investigate the response to three past changes in the earnings test rules, each applying to some age groups and not others. I find that beneficiaries bunch in substantial numbers just below the earnings threshold, and the bunching shifts when the earnings test rules change. These shifts in the budget constraint are incorporated into an econometric model to identify income and substitution effects. The estimation yields significant elasticities that suggest considerable deadweight loss suffered by working beneficiaries.