Originally Published: 25 JAN 23 13:49 ET

By Tami Luhby, CNN

(CNN) -- A record 16.3 million people flocked to the Affordable Care Act exchanges for 2023 coverage, the Centers for Medicare and Medicaid Services said Wednesday.

Open enrollment on the federal exchange and most state marketplaces ran from November 1 to January 15. But those who lose health insurance coverage, have a qualifying life change or have very low incomes can obtain policies throughout the year through special enrollment periods.

Sign-ups on the federal exchange, healthcare.gov, have skyrocketed nearly 50% since the Biden administration took office in 2021, thanks in large part to enhanced federal premium subsidies and increased outreach efforts. Plan selections are up 13% from this time last year.

"The savings are real. The benefits are real," said Health and Human Services Secretary Xavier Becerra.

The spike in coverage helped drive the nation's uninsured rate to an all-time low of 8% in the first quarter of 2022.

Some 3.6 million people -- or 22% -- were new to Obamacare coverage for this year, while the rest were existing enrollees who picked 2023 policies or were automatically reenrolled.

Interest was strong in several of the 11 states that have yet to expand Medicaid to lower-income residents, including Florida and Texas, which saw 3.2 million people and 2.4 million people sign up, respectively.

The data covers the period through January 15 in the 33 states that use the federal marketplace and through January 14 or 15 in the 17 states and the District of Columbia that manage their own exchanges.

The popularity of Obamacare coverage waxed and waned in the 10 years since the initial open enrollment period.

Sign-ups had hit 12.7 million for 2016 coverage under former President Barack Obama, who signed the Affordable Care Act into law in 2010. It then slid to 11.4 million for 2020 coverage under former President Donald Trump, who tried to repeal the landmark health reform law during his term.

Generous federal subsidies to purchase coverage

Affordable Care Act plans have become more attractive since 2021, when the Democrats who controlled Congress at the time temporarily enhanced the program's federal subsidies as part of the Covid-19 relief package known as the American Rescue Plan. Lawmakers extended that generous help through 2025 as part of the Inflation Reduction Act -- the climate, health care and tax package that became law last summer.

Enrollees pay no more than 8.5% of their income toward coverage, down from nearly 10% prior to the enhancement. Lower-income policyholders can receive subsidies that eliminate their premiums. Also, those earning more than 400% of the federal poverty level are now eligible for help.

The assistance allows 4 out of 5 enrollees to find plans that cost less than $10 a month and saved enrollees an average of $800 a year in premiums last year, according to CMS.

Also, more families are eligible for subsidies on the exchanges this year after the Biden administration finalized a rule addressing the "family glitch." The rule allows family members of workers who are offered affordable single coverage but unaffordable family policies to qualify for subsidies on the Obamacare exchanges for the first time.

About 1 million people are expected to either gain coverage or see reductions in premiums, according to the White House.

To inform Americans of these changes and help them pick plans, the Biden administration has poured funds into enrollment assistance and marketing over the past two years.

About 5 million uninsured people were eligible for a 2023 Obamacare plan that is essentially free, according to a recent Kaiser Family Foundation analysis. In many cases, the policies also have cost-sharing subsidies that significantly lower deductibles.