Enrollment is now open to apply for or renew health insurance under the Affordable Care Act, including the expanded Medicaid program.

The deadline to enroll is Tuesday, Dec. 15; those who qualify for Medicaid under the program have until Thursday, Dec. 31, it has been announced.

The deadline is to ensure coverage beginning Jan. 1, 2021.

The nonprofit alliance Enroll Virginia has navigators who can assist people with enrollment or renewal at www.enrollva.org or (888) 392-5132.

In 2019, about 712,000 people, or at least 10 percent of Virginia adults, remained uninsured, state data indicates. That number is expected to be higher now because of layoffs, furloughs and bankruptcies from the coronavirus pandemic. However, many of those who lost jobs may qualify for health insurance coverage through the state’s expanded Medicaid program.

Ironically, open enrollment is going on as the U.S. Supreme Court considers whether the ACA is still constitutional. Oral arguments were heard Tuesday at the court in Washington, D.C., with a decision expected next year.

Also known as Obamacare, the ACA has two elements — providing the government’s Medicaid insurance program to individuals and families with incomes at or below 138 percent of poverty and offering private insurance to those with incomes too high to qualify for Medicaid, whose employer does not offer health coverage or who are self-employed.

During the current year, enrollment in the Virginia’s expanded Medicaid program has grown by 70,000 people. In all, 452,000 people were covered through the expansion as of August, the state noted, lifting the total number covered by Medicaid to 1.5 million state residents.

Estimates suggest that 10 to 15 percent of those who could qualify have yet to enroll. Individuals with incomes up to $17,609 a year, or $29,973 for a family of three, qualify, according to the state.

Meanwhile, about 269,000 Virginia residents took advantage of the ACA’s private insurance offering through the government’s Health Insurance Marketplace, Healthcare.gov, according to state data.The program offers subsidies for those with incomes between 138 percent and 200 percent of the poverty line, or $25,520 for an individual and $43,440 for a family of three.

About 84 percent of marketplace enrollees qualify for financial help with their premiums, resulting in average premiums under $100 per month, state officials said.

Nine companies are competing to be providers for state residents this year. While Virginia Premier is leaving the marketplace, a new arrival, Optimum Choice, is joining.

Three companies — Anthem Health Keepers, Cigna and Optima — listed by the state as insuring the largest number of people applying through the ACA program offer plans in the Richmond area.

To initiate coverage, go to the Health Insurance Marketplace at www.healthcare.gov or call (800) 318-2596. TTY service users should call (855) 889-4325. Language services also are available, according to the state.