Perhaps the biggest frustration with the administration's Obamacare enrollment reports is that they're not really enrollment reports.

Instead, the reports count the number of people who have "picked a plan." But not all of those people have paid, which means not all of them are truly enrolled in health coverage.

How many haven't paid? That's hard to say. In scattered news reports, several insurers have indicated that about 20 percent of people who signed up didn't pay for the first month. But administration officials say they do not know, and are not systematically collecting that information.

However, the administration may have access to that information anyway, an unnamed insurance company source tells Politico:

The latest administration figures show that 4.2 million people have selected health plans in the new insurance markets. Insurance industry officials at four of the big national health plans tell POLITICO that about 15 to 20 percent of people who have signed up have not yet paid their first monthly premium — the final step to get coverage. And they've told the White House that, too, insurance industry officials say. "They have a lot more information than they're letting on," one industry source said of the Obama administration. "They have real hard data about the percent that have paid … If they have not processed those yet and compiled the data, that is a choice they are making. But they have that data now."

Obviously we don't know what insurance company information has or hasn't been shared with federal officials, but it's hard to believe that the administration has not inquired about payment rates or attempted to ascertain what the true enrollment numbers might be. The administration might not be collecting that data, but officials are probably aware of more than they're letting on.