More than two million sign-ups for health insurance through President Obama's health care law, or one out of four, contain data inconsistencies that could mean individuals are getting the wrong amount of federal subsidies, the Associated Press has reported.

When individuals fill out an application for insurance on one of the health care law's exchanges, they have to provide personal information, such as income and citizenship status, to help determine the amount of subsidies, if any, for which they qualify.

But according to the AP, in 2.1 million cases, the information that was provided by applicants conflicted with information on file in federal databases. The story cites a slide presentation by the Department of Health and Human Services that the AP obtained from congressional committees.

More specifically, according to the AP, of the flawed applications, "about 1.2 million have discrepancies related to income; 505,000 have issues with immigration data, and 461,000 have conflicts related to citizenship information."

HHS insisted to the AP that the problem is being resolved — that in the "vast majority" of cases the inconsistency has proven the applicant was correct — perhaps because the government had outdated information.

The New Republic's Jonathan Cohn, a longtime defender of Obamacare, made the case that the issue wasn't likely to be a big deal based on what he was able to gather from speaking with administration officials.

But 2.1 million represents a lot of sign-ups. Even if a "vast majority" of instances are easily resolved, that could still leave hundreds of thousands of cases in which individuals received incorrect subsidy determinations.

If individuals received extra subsidy money, it would mean that they would have to pay it back in the following tax year. A higher-than-expected tax liability could become a mess for lower-income Americans who budgeted for the year based on certain assumptions.

It's also worth recalling that one of the contentious areas of the health care debate involved whether subsidies could be going to individuals who were in the country illegally. Democrats insisted that this wouldn't happen, while Republicans questioned whether proper measures were in place to prevent it. This was the impetus for Rep. Joe Wilson's "you lie" outburst during Obama's September 2009 health care speech to a joint session of Congress.

But this latest news raises questions about whether there are illegal immigrants who are currently getting subsidies.

As with all health care-related news, it will take some time to grasp the seriousness of this problem.