(CNN) -- Around one in five people who picked health insurance policies on the state and federal exchanges last year haven't paid their first month's premiums, according to insurers polled by CNNMoney. These folks will likely see their policy selection canceled and they'll be left uninsured.
Some 2.1 million people signed up for a plan in time for their coverage to start January 1, according to the Obama administration. But with the payment deadlines stretching until January 31 at the latest, anywhere between 12% and 30% of those folks still haven't paid up, insurers say.
Most consumers were given until the middle or the end of January to pay their first premium, a necessary step to actually activating enrollment. Exchange officials and insurers repeatedly stressed the importance of sending in that first payment, with some following up with the slackers by phone or letter.
The true enrollment figure likely won't be known for a few weeks.
Scott & White Health Plan reached out 10 times to each person who hadn't paid and delayed the deadline to Jan. 30, said Allan Einboden, chief executive. Early on, people said there were confused about what they needed to do to activate their policies. Others, however, said they were looking at alternative options or were considering forgoing coverage.
The Texas-based insurer expected its payment rate to be in the high 80% range by its deadline, Einboden said, noting that about 450 people had signed up for coverage starting Jan. 1.
Other insurers cited figures in a similar range. More than 70% of those who signed up for Aetna (AET, Fortune 500) plans sent in payments by its mid-month deadline, while 88% of Medical Mutual of Ohio's 6,500 applicants paid their bill by the Jan. 15 cutoff. That was more than Medical Mutual had projected.
A majority of WellPoint's would-be members have paid, said WellPoint's chief financial officer, but not a "vast majority." WellPoint (WLP, Fortune 500), a major player in the exchanges with 500,000 applications, has given folks until Jan. 31 to pay.
Those who don't pay are receiving termination letters. CoOportunity Health said about 18% of the 11,000 Nebraska and Iowa residents who had signed up missed its Jan. 24 payment deadline and would receive cancellation notices this week. But even this final notice told recipients to call if they had intended to pay the premium.
The insurer had projected up to 20% wouldn't activate their enrollment.
"We figure either those people had a change of heart or thought it was too expensive," said Cliff Gold, CoOportunity's chief operating officer. "Or maybe some people decided to keep what they had."
Insurers are generally pleased with the payment rates, though they are grousing about having to weed out the deadbeats, said Paul Tiede, an executive vice president at SunGard, which works with insurers on billing. There's been a huge uptick in payments in recent weeks.
"Money is flowing in the door," Tiede said.
Now insurers have to start tallying the next wave of payments. Most of those who signed up this month for coverage to start Feb. 1 have until Friday to pay and activate their enrollment.