SUNDAY, Dec. 29, 2013 (HealthDay News) -- After a disastrous introduction back in October, the federal government's HealthCare.gov insurance coverage website saw a surge of enrollments in December, government officials said Sunday.

More than 1.1 million people enrolled in a qualified health plan through the federally operated marketplace, or exchange, from Oct. 1 through Dec. 24. More than 975,000 of those enrollments came in December, Marilyn Tavenner, administrator for the Centers for Medicare & Medicaid Services, said in a blog post.

"Our HealthCare.gov enrollment nearly doubled in the days before the Jan. 1 coverage deadline compared to the first few weeks of the month. December enrollment so far is over seven times that of October and November. In part, this was because we met our marks on improving HealthCare.gov: the site supported 83,000 concurrent users on Dec. 23 alone," Tavenner said.

"We expect to see enrollment ramp up over time, much like other historic implementation efforts we've seen in Massachusetts and Medicare Part D," the federal government's prescription drug program, she added.

Sunday's announcement made no mention of the 14 exchanges that are run by states, independent of the federal website, as part of the Affordable Care Act, the Obama Administration's massive overhaul of health care. Some states -- such as California, Connecticut, New York and Washington -- have said their websites are operating well, while other states have encountered problems.

It's also not clear how many of the new enrollees are young adults. Their financial participation through insurance premiums is considered crucial to the success of the Affordable Care Act, sometimes referred to as Obamacare. Young adults typically have fewer health insurance claims than older adults, who tend to become sicker as they age. So premiums from younger adults are needed to help fund the program.

Sunday's announcement also marked some rare positive news about the rollout of the insurance enrollment process. HealthCare.gov was plagued for weeks with computer glitches that frustrated consumers who weren't able to sign up for coverage.

As recently as Tuesday, Dec. 24, the Obama Administration once again extended the deadline for people to register for health insurance coverage on Healthcare.gov. The extension followed a 24-hour "grace period" that was granted on Monday, Dec. 23 -- beyond the original enrollment deadline of Monday, Dec. 23 at 11:59 p.m. -- for benefits that would take effect Jan. 1.

In most states, Monday, Dec. 23 had been the deadline for selecting a plan that would take effect on the first day of the new year.

Under the Affordable Care Act, most adults will pay a $95 penalty -- or 1 percent of income -- in 2014 if they don't have health insurance coverage. The penalty rises to $695 -- or 2 percent of income -- by 2016.

To avoid the penalty, people must enroll in a plan by Feb. 15 or qualify for an exemption from the penalty.

If you're in the market for health insurance, here are some key questions and dates to keep in mind:

Can I enroll after Jan. 1?

Open enrollment for 2014 runs through March 31. If you buy coverage, say, on Feb. 10, it won't kick in until March 1. If you wait until March 31, your policy will take effect May 1.

There is no deadline for signing up for Medicaid or the Children's Health Insurance Program.

If I enrolled in a private health-exchange plan by Dec. 23, when is my premium due?

Recently, the federal government directed insurers to accept payment by Dec. 31 and encouraged health plans to push the deadline further.

Consumers who signed up by Dec. 23 and pay the first month's premium by Jan. 10 will have coverage on Jan. 1, the industry group America's Health Insurance Plans announced this month.

However, the federal government cautions that not all health insurers are extending the payment deadline, and some may require payment on or before Dec. 31, 2013.

More information

Need help with your insurance application? HealthCare.gov has tips for getting health insurance coverage.