Lawful marriage between spouses of the same sex. Same-sex marriage is legal and recognized in every U.S. state and the District of Columbia. As long as a same-sex couple is married in a jurisdiction with legal authority to authorize the marriage, a health insurance company that offers health coverage to opposite-sex spouses must do the same for same-sex spouses. The Health Insurance Marketplace also treats married same-sex couples the same as married opposite-sex couples in every state when they apply for premium tax credits and lower out-of-pocket costs on private insurance plans.