Hundreds of thousands received Obamacare extensions

Hundreds of thousands of people are likely still "in line" to sign up for Obamacare. Maybe more.

The open enrollment period officially ended at midnight on March 31. But most state exchanges, Washington, D.C., and the 36-state federal exchange instituted extended enrollment for people who can prove or attest that they attempted to sign up before then, and ran into technical or other obstacles.

Source: Healthcare.gov

The Department of Health and Human Services, which oversees HealthCare.gov, won't say how many people have applied or qualified for this special enrollment period. But a few states have, and the numbers indicate there are a lot of people out there still eligible to pick a plan under the Affordable Care Act.

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Minnesota told CNBC about 36,000 people filled out enrollment-attempt forms. That is a huge number, when you consider a total of 47,046 had completed their enrollment by the March 31 deadline.

Hawaii had 1,280 people fill out attestation forms. That may not sound like much, but it's about one-sixth of the 7,596 enrollments completed there from Oct. 1 through March 31.

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Kentucky said about 8,000 people who were found eligible for a subsidy have yet to select a plan, and they are eligible to do that until April 15. The state anticipates "several thousand more" to attest to encountering trouble, and becoming eligible to enroll over the next seven days.

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And in Nevada, 89,211 people have gone all the way through eligibility determinations and have not selected a plan. As in Kentucky, all of them are still eligible to complete enrollment. Nevada is also still collecting attestations from people who want to qualify for the special enrollment period.

HHS said more than 7 million people picked an ACA plan as of March 31. That number is likely to increase during the special extended enrollment, which varies from state to state.

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But what will really count, is how many of those people go ahead and pay their first premium.

In the 10 states that have released such data to CNBC, about 1.27 million people have paid. That includes California, where 85 percent of its more than 1 million enrollees have done so.

It's impossible to come up with an overall average rate of payment, as some states are now reporting only paid enrollments, including Washington (146,497), Vermont (48,780) and Massachusetts (29,534).

—By CNBC's Jodi Gralnick.