Even as federal officials catch heat for not disclosing how many Obamacare enrollees nationwide have actually paid their first insurance premiums, nine states and the District of Columbia have been releasing such data publicly.
Those states are seeing a wide range of outcomes in the rate of people who sign up for insurance plans on their government-run exchanges and make their first month's payments. That payment is required for people to actually be enrolled and eligible for health benefits under the plans.
Connecticut, whose Obamacare marketplace has been seen as a star of the state-run exchanges, leads the pack in paid enrollments. In the Nutmeg State, 92 percent of its 57,465 Obamacare sign-ups have coughed up the cash to make their enrollment official.
"It's never going to be 100 percent," said Kevin Counihan, CEO of Access Health CT, the state's marketplace. But, he added, "we're working very aggressively through health plans to get the other 8 percent in."
(Read more: House GOP wants Obamacare payment data)
Minnesota is in second place, with 90 percent of enrollees paid.
California, whose 923,832 sign-ups make it the leader by far in nationwide Obamacare enrollment, is in third place, with 85 percent reported paid enrollment.
Maryland is dead last. The state's exchange, which has been a technological disaster, saw just 54 percent of enrollees paying for their first premiums as of March 1.
The exchanges operated by Washington state and Vermont also failed to crack 60 percent.
Five states that run their own Obamacare exchanges are not releasing the paid rate for the Obamacare exchanges they operate. And Massachusetts only reports paid enrollments; it does not report totals of people who have signed up for plans, meaning that the paid rate is unknown.
(Read more: Obamacare's problem: Can't fix stupid)
Insurance experts estimate that nationwide, anywhere between 15 percent and 20 percent of Obamacare enrollees haven't paid.
The gap between paid enrollments and the number of people who have selected plans can result from many factors, including people deciding their plan was too expensive, moving out of state, getting a job that has insurance and from duplicate enrollments for the same individuals or families.
In the cases of some states, people are reported as unpaid even in cases where they might not have even yet received a bill from the plan they've enrolled in. Experts expect the unpaid rate to decline in many states as people voluntarily pay or get pestered by insurers to do so.
But ongoing disclosures by nine states and D.C. about the data they have stand in sharp contrast to HealthCare.gov, the federally run Obamacare marketplace that serves 34 states.
(Read more: Castlight near $1 billion IPO)
Federal officials for months have been unable—or unwilling—to release paid enrollment data from those 34 states even as they give monthly updates on total sign-ups nationwide.
Fed up with lack of official nationwide data, Republicans in the House of Representatives on Thursday sent letters to all insurers selling plans on HealthCare.gov asking them for their own paid enrollment rate.
"There's never been a question of if the administration could get the most accurate enrollment data, it's just a question of if they would choose to be transparent with the American people. We know, unfortunately, that they have chosen to bury the facts which is why the Energy and Commerce Committee is seeking answers," said Rep. Marsha Blackburn, a Republican from Tennessee, who is the vice chairman of the committee.
House Republicans oppose Obamacare, and are likely to use data that lowers the officially reported enrollment to buttress their argument that the Affordable Care Act is falling far short of its goal of providing health coverage to tens of millions of uninsured people.
| State | # of people who selected a plan | % who have paid |
|---|---|---|
| Connecticut | 57,465 | 92% |
| Minnesota | 33,722 | 90% |
| California | 923,832 | 85% |
| Rhode Island | 19,690 | 83% |
| DC | 6,516 | 75% |
| Nevada | 30,015 | 70% |
| Vermont | 24,326 | 59% |
| Washington | 191081 | 57% |
| Maryland | 38,070 | 54% |
Source: Source: Individual State Exchanges
As of Feb. 28, about 4.2 million people nationwide had enrolled in Obamacare plans, according to federal officials. Recent data assembled by CNBC suggests that as many as 4.45 million have enrolled as of Thursday, but that remains more than 1.5 million short of the administration's revised goal of 6 million enrollees by March 31.
"We are focused on providing reliable and accurate information and right now, we do not have full, complete, accurate data on individuals who have paid their plans," a spokesman for the federal Centers for Medicare and Medicaid Services said Thursday, after Republicans criticized the administration for not releasing that data.
On Friday, President Barack Obama said that enrollment was high enough to make .
"Well, at this point, enough people are signing up that the Affordable Care Act is going to work," Obama told WebMd, in an interview aimed at promoting the health-reform law as it nears the end of the enrollment period for this year on March 31.
Dan Mendelson, CEO of the consulting company Avalere Health, said the Obama administration is in an awkward position, because the paid enrollment rate is a fluid number, and one that could hurt the administration politically and "helps the Republicans."
"It doesn't help them to put out that number. It's going to be lower than enrollment no matter what," said Mendelson. "It doesn't help them in any way to move the goalposts and make the field longer."
Mendelson said that paid rate is "a difficult number to understand" because "it's a snapshot of a period of time," and will continue changing until after the close of open enrollment.
He said that once the open enrollment period closes, he expects that between 5 percent and 10 percent of Obamacare enrollments will end up being unpaid. Before the launch of Obamacare, the industry standard was a 10 percent unpaid rate for people who enrolled in individual insurance plans, Mendelson said.
Mendelson said that after taking into account the unpaid rate he expects, he estimates that total actual enrollment in Obamacare will be "somewhere between 5 million and 5.25 million" by the end of March. That would be as much as 16 percent less than the revised 6 million target set by the administration last month.
—By CNBC's Dan Mangan and Jodi Gralnick. Follow them on Twitter @_DanMangan and @jodigralnick.