Supreme Court rulings in 2013 and 2015 established and expanded rights to same-sex marriage in the U.S. One of the most visible and impactful ways the federal government recognized these new rights was by allowing—indeed, requiring—legally-married same-sex couples to file federal tax returns as married couples. In this brief, we estimate how many couples took up these new federal rights in each state, drawing from returns filed in the years affected by the Court decision