The Affordable Care Act (ACA, also called "Obamacare") was enacted in March 2010 with the goal of making affordable health insurance available to more people. In addition, it expanded the Medicaid program in many states.
With the ACA came tax penalties for uninsured and underinsured taxpayers that didn't qualify for an exemption. However, starting in tax year 2019, the Tax Cuts and Jobs Act eliminated the penalty on federal tax returns.
Health Insurance Marketplaces, or exchanges, were created by the ACA to provide health plan shopping and enrollment services to individuals, families and small businesses. HealthCare.gov is operated by the federal government and a few states run their own state Marketplaces.
When you purchase health insurance from a Marketplace, you may qualify for a Premium Tax Credit (PTC) to help make your health coverage more affordable.
You can purchase health insurance during a yearly open enrollment period that runs from November 1 through January 31. The only other time you may be able to enroll is when you’ve had certain life events, including losing health coverage, moving, getting married, having a baby, or adopting a child.