The action could shield from deportation millions of immigrants who are in the country illegally, including hundreds of thousands in California. That would result in many becoming eligible for government services like public healthcare.
Others could receive help through state programs that provide caregivers or cash assistance for the elderly and disabled.
No funding has been set aside in Gov. Jerry Brown's latest budget proposal to cover newly eligible immigrants, and it's unclear how much money would be needed.
"The potential fiscal impact of these actions ... is highly uncertain," according to legislative analysts, who provide nonpartisan advice to state lawmakers.
Healthcare and home care programs are jointly funded by the state and the federal government. The cash assistance is provided solely by the state.
California has filed a legal brief in support of Obama's immigration plan, which is being challenged in court by 26 states.