If the person doesn't qualify as your dependent (e.g., an adult child over 26 or a friend), you can still help them get covered through the Health Insurance Marketplace: Who's included in your household | HealthCare.gov
Many employer-sponsored and some state-specific plans allow unmarried partners if you provide proof of cohabitation or shared finances. can i buy health insurance for someone else
Almost all plans allow you to add a legally married spouse. If the person doesn't qualify as your dependent (e