Same-sex marriage refers to 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 (Washington, D.C.).

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 federal 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.

In Massachusetts, same-sex marriage has been legally recognized since May 17, 2004, following the Massachusetts Supreme Judicial Court's decision in Goodridge v. Department of Public Health. This landmark ruling made Massachusetts the first state in the U.S. to legalize same-sex marriage. Consequently, health insurance companies in Massachusetts are required to offer the same health coverage benefits to same-sex spouses as they do to opposite-sex spouses. This includes the provision of premium tax credits and lower out-of-pocket costs on private insurance plans, in accordance with federal regulations. The federal Health Insurance Marketplace® applies these provisions uniformly across all states, ensuring that married same-sex couples are treated the same as married opposite-sex couples for the purposes of federal health insurance benefits.