SACRAMENTO, Calif. (AP) — The new year brought relief for Americans who previously had no health insurance or were stuck in poor plans, but it also led to confusion after the troubled rollout of the federal health care reforms sent a crush of late applications to overloaded government agencies.

That created stacks of yet-to-be-processed paperwork and thousands — if not millions — of people unsure about whether they have insurance.

Mike Estes of Beaverton, Ore., finally received his insurance card on Dec. 27 after applying in early November. Still, the family was thrilled to have insurance through the Oregon Health Plan, Oregon's version of Medicaid, because their previous $380-a-month premium "literally crushed our family's finances," Estes said.

Obama administration officials estimate that 2.1 million consumers have enrolled so far through the federal and state-run health insurance exchanges that are a central feature of the federal law. But even before coverage began, health insurance companies complained they were receiving thousands of faulty applications from the government, and some people who thought they had enrolled for coverage have not received confirmation.

Tens of thousands of potential Medicaid recipients in the 36 states relying on the federal exchange also are in limbo after the federal website that was supposed to send their applications to the states failed to do so.

Reports of other complications were scattered around the country.

In Burlington, Vt., the state's largest hospital had almost two dozen patients seek treatment with new health insurance policies, but more than half of those did not have insurance cards. Minnesota's health care exchange said 53,000 people had enrolled for coverage through its marketplace, but it was unable to confirm the insurance status of an additional 19,000 people who created accounts but did not appear to have purchased plans.

In Connecticut, officials were pleading for patience as call centers fielded calls from people who are concerned because they had yet to receive a bill for premiums or an insurance identification card.

"This is an unprecedented time, because there are a record number of people who have applied for coverage with an effective date of Jan. 1," said Donna Tommelleo, a spokeswoman for the Connecticut Department of Insurance.

But the volume was no higher than usual on Thursday at the call center serving the federal health care exchange, where the vast majority of calls were from consumers seeking coverage starting Feb. 1, U.S. Health and Human Services spokeswoman Joanne Peters said.

The agency is coordinating with "insurers, providers, hospitals, and pharmacists to help smooth the transition for consumers who are using their new plans for the first time," she said in an emailed statement.

The major pieces of the Affordable Care Act that took effect with the new year mean people with pre-existing medical conditions cannot be denied coverage, yearly out-of-pocket medical expenses will be capped and new insurance policies must offer a minimum level of essential benefits, ranging from emergency room treatment to maternity care.

Some parts of the law took effect previously, such as the ability of young people to remain on their parents' insurance policies until age 26.

Minnesota and Rhode Island were among the states that extended their sign-up period to the final day of 2013, leading to a crush of new paperwork that government agencies and insurance companies were still scrambling to process. Many consumers have yet to receive bills or insurance cards.

Julie Cadorette, 63, of Maynard, Mass., said she has spent dozens of hours on the phone trying to find out the status of her application through Massachusetts Health Connect, which she said she sent by certified mail three months ago. Her current plan ends Jan. 31.

"It's very hard to deal with them, they're so behind," she said Thursday. "When you call them, they ask you specific questions. You can't ask them any questions."

Massachusetts consumers whose applications for subsidized insurance have not been processed by the time their coverage expires will be temporarily covered under the state's version of Medicaid, MassHealth spokesman Jason Lefferts said.

The new year brings the most personal test yet for President Barack Obama's health care overhaul as millions of patients begin to seek care under its new mandates. The burden for implementing the law now shifts to insurance companies and health care providers.

Dr. John Venetos, a Chicago gastroenterologist, said there was "tremendous uncertainty and anxiety" among patients calling his office.

"They're not sure if they have coverage. It puts the heavy work on the physician," Venetos said. "At some point, every practice is going to make a decision about how long can they continue to see these patients for free if they are not getting paid."

New York is allowing a grace period for those whose policies start Jan. 1 but whose premiums are not due until later. In those cases, state health officials and insurers say people should pay the doctor's bill and then submit it for reimbursement.

It will not be known for a couple of weeks how many of those who signed up for coverage in the exchanges follow through and pay their premiums or how many are stuck in backlogs of unprocessed applications.

In California, employees of the state health exchange were still going through some 19,000 paper applications sent in the early days after Covered California launched on Oct. 1, spokesman Dana Howard said. He could not say how many were outstanding.

The entire tracking system was "in a sort of chaos" Thursday as consumers tried to use or confirm their new insurance, said Kelly Fristoe, an insurance agent in Wichita Falls, Texas.

"I've got pharmacies that are calling in to verify benefits on these new plans that are getting incorrect information," he said. "I have people that are calling to make their initial premium payment, and they've been on hold for maybe three or four hours at a time and then they get hung up on."

People who signed up on the federal website have until Jan. 10 to pay premiums for coverage retroactive to Jan. 1, while consumers in some states have until Jan. 6.

Premiums paid after the deadline will be applied to coverage starting Feb. 1 or later. Consumers have until March 31 to sign up in time to avoid a federal tax penalty for remaining uninsured. That fine starts at $95 for an individual this year but climbs rapidly, to a minimum of $695 by 2016. There is an additional fine for parents who do not get health insurance for their children.

Medicaid, the state-federal health insurance program for the poor, already was experiencing problems in some states.

In Pennsylvania on Thursday, Gov. Tom Corbett's office cautioned that people who applied for health insurance through the federally run website and were found to be eligible or potentially eligible for Medicaid might not have coverage. The state was still waiting for the federal website to transfer electronic files for more than 25,000 applications.

"We are doing everything we can to ensure these individuals receive the coverage they've applied for as quickly as possible," said Eric Kiehl, spokesman for the Pennsylvania Department of Public Welfare.

Anticipating disruptions, major drug store chains such as CVS and Walgreens as well as smaller pharmacies have announced they will help customers with coverage questions, even providing temporary supplies of medications without insisting on up-front payment.