Up to 115,000 people stand to lose Obamacare health insurance coverage by Sept. 30, and another 336,000 people are at risk of losing federal subsidies to pay for that coverage, officials revealed Monday.
The 115,000 people failed to show valid proof of citizenship or legal residency for the insurance plans they bought through HealthCare.gov, a top federal official revealed Monday.
But the Obama administration also said those people with questionable eligibility will be able to keep their coverage if they continue paying their premiums, provide documentation showing their legal status in the U.S., and sign up again in their health plans during a special enrollment period.
If they don't, "at the end of September, they'll be terminated," said Andy Slavitt, principal deputy administrator of the Centers for Medicare and Medicaid Services. Many of those people also will face demands from the Internal Revenue Service that they repay federal subsidies they received this year to help them pay for their health insurance plans.
The administration also said it was warning another 336,000 people they need to provide proof of income by Sept. 30, or risk losing those federal subsidies that reduce-often greatly-what they personally pay in monthly insurance premiums.
Without documentation, as of Nov. 1, the subsidies will be changed to reflect the income data that the federal government has about the households in question, Slavitt said. CMS was sending reminder letters to those people Monday.
Those people comprise 279,000 households whose enrollment information, when they applied for Obamacare via HealthCare.gov, contained claims about income that did not match other data the federal government has about them. HealthCare.gov is the insurance marketplace that sells insurance in the 36 states not running their own health exchange.
Under the Affordable Care Act, only U.S. citizens or legal residents are eligible for enrollment in insurance plans sold through the health exchanges.
The amount of money people receive in subsidies, or premium assistance, depends on their income levels; as a rule, people who earn less get more in subsidies.
More than 8 million people enrolled in Obamacare plans by mid-April, the end of open enrollment for 2014. The vast majority, around 86 percent, received some kind of subsidy, because their household income was between about one to four times the federal poverty level, or about $46,000 to $92,400, for a family of four.
About 5.4 million of the nationwide enrollment came via HealthCare.gov.
As of May 30, there were so-called data-matching issues for 966,000 individuals who claimed they were legal residents of the U.S. There were also data-matching problems related to another 1.2 million households whose members were enrolled through HealthCare.gov.
Since then, 851,000 individuals have submitted documentation that they are citizens or legal residents, according to the Centers for Medicare and Medicaid Services. Slavitt said those cases are either "resolved or in the process of being resolved."
Another 897,000 households have submitted proof of income qualifying them for subsidies. As of Sunday, about 467,000 households with income data-matching issues have been closed, and another 430,000 or so are in the process of being resolved, CMS said.
The remainder not only face the prospect of losing their subsidies after Nov. 1, but also may be forced to repay the difference between what they were eligible for in terms of subsidies, and what they actually received.
Slavitt said that problems with matching data submitted by enrollees applying for insurance will happen again in future Obamacare enrollment cycles, including the second one, which is due to begin Nov. 15.
"This year isn't a one-time event," Slavitt said. "Circumstances in peoples' lives will always change."
Monday's announcement by CMS only related to enrollees in states served by HealthCare.gov.
There are an unknown number enrollees in other states who have similar questions about their eligibility.
The 14 states and the District of Columbia that are running their own Obamacare exchanges are handling eligibility questions about their own enrollees in a a variety of ways, and with different deadlines.
CNBC reached out to all of those exchanges, and received answers from eight about their policies on eligibility documentation issues.
Kentucky's health-care exchange, known as kynect, gave slightly more than 1,700 people until last Wednesday to provide evidence of citizenship or legal immigration status.
California, which has by far the most enrollees of any single state-run exchange, has set Sept. 30 as a deadline for the approximately 148,000 people who were sent notifications asking them to submit evidence of insurance eligibility or lose coverage.
In Massachusetts, if the exchange has questions about someone's status, enrollees will be sent a notice and will have 90 days to respond.
Rhode Island's exchange had a deadline of Monday for slightly more than 900 enrollees to verify their eligiblity.
The New York State of Health marketplace "has not issued a notice like the one issued by the federal marketplace," according to a spokeswoman.
"During the application process, NYSOH notifies any consumer who is unable to verify their immigration status that they must upload, mail or fax proof of citizenship/immigration status to the customer support center within 90 days," the spokeswoman said. "NYSOH is currently in the process of reviewing accounts and has not terminated anyone's coverage for lack of compliance with this requirement.
Washington state's exchange has a similar policy.
"Here in Washington we do not have a hard deadline for customers to submit documents to verify citizenship or lawful presence," a spokeswoman said. "But we do require people to submit the necessary documents to Washington Healthplanfinder within 90 days of applying for coverage. It's extremely important for customers to provide these documents within 90 days so their coverage isn't terminated."
A spokeswoman for Minnesota's health insurance exchange, known as MNSure, said that marketplace likewise has not set a hard deadline yet.
"MNsure is currently working to finalize the number of consumers who need completed verifications," the spokeswoman said. "Once this universe is identified, we will determine appropriate next steps. A significant number of consumers who may have one of these issues have not received notices yet. It is our intention to address verification issues before open enrollment begins in November."
Hawaii's health-care exchange is still working to determine how many enrollees have questionable documentation for eligibility, and as a result has set a much later deadline for enrollees to submit necessary documents.
Tom Matsuda, interim executive director of the Hawaii Health Connector, said "Enrollees in the Hawai'i Health Connector whose immigration or citizenship status is not verified will have until Dec. 31, 2014 to submit documentation."
-By CNBC's Dan Mangan