Americans hit with the new federal tax penalty for not having health insurance coverage will have more time to purchase a health plan this year, the Obama administration announced Friday morning following pressure from Democratic lawmakers.

Up to 6 million Americans are expected to face the Affordable Care Act penalty for not having health insurance in 2014, according to administration projections. Those living in 37 states relying on the HealthCare.gov enrollment portal who would have to pay the 2014 and 2015 penalty will have a new opportunity to purchase coverage between March 15 and April 30, the administration said.

The Friday announcement was largely anticipated after senior Democrats and groups supporting the law recently pushed the administration to create a special enrollment period for those facing the individual mandate penalty for the first time. The groups feared that without this enrollment window announced Friday, millions just learning about the penalty wouldn't be able to avoid paying it again next tax season.

Administration officials said they didn't have any projections for how many people will sign up during this special enrollment period. "Our intention in doing this is not to increase numbers for numbers' sake," said Andy Slavitt, principal deputy administrator for the Centers for Medicare and Medicaid Services, the agency overseeing HealthCare.gov. "If there were people who were unaware of the fee, this is the way they become aware."

Past surveys have shown that nearly half of uninsured adults were unaware of the penalty for not having coverage. Among the uninsured, there's also still considerable unawareness of the new insurance scheme established under the ACA. Just about one-third of uninsured adults said they heard of the health insurance exchanges and knew they had until February to obtain coverage, the Urban Institute's Health Reform Monitoring Survey found in December.

The penalty for being uninsured in 2014 starts at $95 or one percent of annual household income, whichever is greater. The minimum penalty in 2015 more than triples to $325 or two percent of annual income, whichever is greater.

To qualify for this special enrollment period, consumers must attest that they haven't purchased 2015 coverage and that they paid the fee for not having health insurance in 2014. They must also attest that they only became aware of the individual mandate penalty after the regular 2015 enrollment window closed.

Before Friday, some states running their own marketplaces, including Minnesota and Washington state, already announced they'd allow people who were hit with the penalty more time to purchase coverage. Other states running their own insurance marketplaces may follow Friday's CMS announcement.

About 11.4 million people had signed up for 2015 exchange coverage by the end of open enrollment last Sunday. The administration had already announced that an estimated 150,000 people who had started a HealthCare.gov application before that deadline will have until Sunday to finish it for coverage starting March 1.

In less than two weeks, the Supreme Court will hear a lawsuit challenging the legality of subsidies provided through nearly three dozen states relying on the federal-run exchange. If the court sides with the challengers, about 85 percent of people who signed up for coverage on HealthCare.gov will lose subsidies that, on average, discounted monthly premiums by about 75 percent.

CMS also said it’s notifying about 800,000 individuals that they received an incorrect tax filing form to reconcile their 2014 health insurance subsidies. About 50,000 people had already filed these forms, Slavitt said.