More than 1 million people may be in jeopardy of paying back a portion of their ObamaCare subsidies because of discrepancies between their applications and federal records.
Another roughly 966,000 have discrepancies related to citizenship or immigration status, according to federal health officials.
The problem was uncovered in a federal document obtained Wednesday by the Associated Press. The slide presentation revealed that 2.1 million people had inconsistencies in their exchange applications at the end of April.
A spokeswoman for the rollout said most of the cases are being resolved in favor of consumers and can be explained by outdated government records.
"The fact that a consumer has an inconsistency on their application does not mean there is a problem on their enrollment," Centers for Medicare and Medicaid Services (CMS) spokeswoman Julie Bataille told the AP.
"Most of the time what that means is that there is more up-to-date information that they need to provide to us."
But the inconsistencies point to the possibility that many enrollees obtained coverage or subsidies without being eligible.
The House Energy and Commerce Committee pegged the number of enrollments with discrepancies at roughly 4 million as of May 27, a figure that was immediately disputed by Democrats.
The number came from a set of documents obtained by the committee from Serco, a contractor working to alleviate the backlog, GOP staffers said. But Dems argued that it included roughly 2 million enrollments that were never completed.
Committee Chairman Fred Upton (R-Mich.) lamented that the "exchanges are still not built and accurate information remains hard to come by."
"Administration officials allowed applications to be processed before the information provided was fully vetted and verified," Upton said in a statement.
"What’s worse is the system to process these discrepancies is still incomplete, leaving an antiquated mail and phone system to address the millions of questions in applications."
A consumer's health coverage will not be affected by a discrepancy for 90 days, giving federal health officials a window to sort out confusion.
Bataille said roughly 60 percent of the 2.1 million are within that 90-day period and can still produce additional documentation to confirm their eligibility for ObamaCare plans or subsidies.
Previous reports have indicated that subsidies issued on the exchanges may have been incorrect for more than 1 million people.
"We are working with consumers every day to make sure individuals and families get the tax credits and coverage they deserve and that no one receives a benefit they shouldn't,” CMS spokesman Aaron Albright said.
“Two million consumers are not at risk of losing coverage – they simply need to work with us in good faith to provide additional information that supports their application for coverage and we are working through these cases expeditiously."
--This report was last updated at 6:15 p.m.