Health and Human Services Secretary Kathleen Sebelius said Monday that insurance companies estimate between 80 and 90 percent of the 6 million people who have signed up for Obamacare have actually paid a premium.

"What we know from insurance companies ... tell(s) us that, for their initial customers, it's somewhere between 80, 85, some say as high as 90 percent, have paid so far," Sebelius said on KWTV-TV. "Lots of companies have different timetables for when their new customers have to send their first payment."

The White House has said more than 6 million people have signed up for Obamacare. But reporters have had little luck getting the administration to provide specific figures when it comes to what percentage of enrollees have actually paid a premium, which Sebelius acknowledged is required before someone is officially enrolled.

"You are not fully enrolled -- you're absolutely right -- until you pay your premium," she said. "But we also know that millions of people now have health care."

If between 80 and 90 percent of the six million have paid premiums, the number who are fully enrolled would be closer to five million than to six million.

Previously, White House press secretary Jay Carney said that general estimates suggest about 80 percent of enrollees had paid a premium.

(h/t BuzzFeed)