More than 4 million Californians will lack health insurance by 2023 because of a pending change in the federal health insurance law that drops an individual mandate to get health coverage, according to a UCLA and Berkeley study released Nov. 27.

The study by researchers at UCLA and UC Berkeley projects the change in the Affordable Care Act effective Jan. 1 to strip the penalty for those who don’t have health insurance will add 800,000 residents to the ranks of uninsured.

California’s implementation of the ACA lowered the number of uninsured from 17.6 percent in 2012 to 10.4 percent in 2016, or 3.6 million residents under the age of 65.

The pending change in the law could drive the rate of uninsured residents to 12.9 percent by 2023, or 4.4 million people, according to the study.

The report suggests policies to help California reduce the projected loss in coverage: expanding Medi-Cal to all low-income residents regardless of their immigration status; providing state subsidies for market premiums; implementing a new state individual mandate; and boosting outreach and enrollment efforts.

“Federal decisions threaten to reverse health coverage gains around the country,” said Gerald Kominski, a senior fellow at the UCLA Center for Health Policy Research, and a co-author of the study. “These policies could help to ensure that California continues to build on its successes and drive toward its goal of achieving universal health coverage.”

The UC Berkeley Labor Center also contributed to the report, which projects the most substantial enrollment changes will occur in the individual market.

Health business reporter Dana Bartholomew can be reached at [email protected]. Follow him on Twitter @_DanaBart.