California's health exchange said an estimated 300,000 people in the state with COBRA insurance coverage can switch to an Obamacare policy through July 15.
The Covered California exchange announced the special two-month enrollment period, starting Thursday, to address confusion about the sign-up rules.
"We think many people on COBRA are confused," said Peter Lee, the exchange's executive director.
The state exchange said the information on its coveredca.com website wasn't clear for people who have lost a job and held on to their employer health plan through COBRA, a federal law known as the Consolidated Omnibus Budget Reconciliation Act.
Under the law, workers who leave their employer can hold on to their existing health insurance for a time but must pay the entire premium on their own.
That makes COBRA coverage fairly expensive for people, particularly those who were laid off and might be unemployed for some time.
The Affordable Care Act offers new options for those people in the individual insurance market. The federal law guarantees coverage regardless of preexisting conditions and provides premium subsidies based on a person's income.
But open enrollment under the health law closed last month and doesn't reopen until November.
Thursday, Covered California clarified that people with COBRA coverage do qualify for special enrollment through July 15.
Lee said some consumers could save thousands of dollars by getting an Obamacare policy instead.
"For many people the cost of a Covered California product will be substantially less," Lee said. "We want to make sure people on COBRA know this is an option. We had an IT glitch that didn’t make it clear."
The state said its move mirrors a ruling this month from the Obama administration that allows COBRA enrollees to buy health plans through a separate federal exchange until July 1.
Special enrollment is also extended to people with other "qualifying life events" such as getting married, having a child or moving to a new area.
Enrollment in Medi-Cal, the state's Medicaid program, runs all year.
Covered California signed up 1.4 million residents in private health plans during the first open-enrollment period for the health law.