WASHINGTON (AP) — For the first time, the federal government will allow Medicaid funds to treat some people in prisons, jails or juvenile detention centers, the Centers for Medicare and Medicaid Services announced Thursday.

CMS will allow California inmates to access limited services, including substance abuse treatment and mental health diagnoses, 90 days before release. Since Medicaid’s inception, federal law has prohibited the use of Medicaid money for people in custody, and inmates have had their health insurance suspended.

The move will provide more stability for inmates and juveniles in custody as they leave institutions and return to the outside world, CMS Administrator Chiquita Brooks-Lasure said Thursday.

She said the change would allow the state to “make unprecedented gains for long-underserved incarcerated individuals.”

At least 10 other states have asked CMS for an exemption from using Medicaid dollars to treat inmates before their release. California could be a model for those states, especially since the program is a new territory for Medicaid and is expected to be a large-scale undertaking, said Vicki Vacino, who oversees the territory’s health and reentry project.

California state officials said Thursday that they hope some inmates will begin accessing services through Medicaid starting in 2024. People who are incarcerated will be screened and evaluated for eligibility to access the state’s Medicaid program. If they are eligible, health professionals will help them develop a care plan for re-entry.

It will take at least two years to roll out the program to all prisons in the state, said Jaycee Cooper, the state’s Medicaid director.

Millions of people are expected to be affected: Every year, California releases nearly half a million inmates from state or county jails, and about 80% of those people qualify for Medicaid.

People leaving prison, jail or juvenile detention often don’t know where to start in getting medical care, Vacina said.

“There’s a huge barrier to care right now when people are leaving jail and prison,” Vacina said. “As you know, a lot of times when they’re released, they’re left to fend for themselves with very, very little support.”