The Obama administration is to provide an exemption for those whose insurance plans were cancelled under the Obamacare law.
The exemption will apply to about 500,000 people who lost their private plans under the law. They will also be able to buy cheaper plans offering minimal insurance coverage levels.
The BBC reports the plans were previously available only to people under the age of 30.
The announcement was issued on Thursday night, just before a deadline of 23 December for purchases of insurance coverage with benefits beginning on 1 January.
The exemption will free who lost private insurance plans under Obamacare from tax penalties they would have faced were they not able to arrange new coverage.
Congresswoman Marsha Blackburn (Republican) said the announcement demonstrated the White House was in "full panic mode" before the deadline.
The BBC reports the Patient Protection and Affordable Care Act has had a troubled rollout.
The federal website has had extensive glitches and performance problems since its launch on 1 October. It became a metaphor as well as a problem in its own right.
Despite a top-to-bottom overhaul of the site in October and November, enrolment numbers continue to be lower than anticipated.
Insurance companies have cancelled millions of medical insurance policies because they did not meet the conditions of Obamacare.
President Barack Obama originally promised that people would be able to keep their existing plans.