Cal. Gov. Code § 9510.5
There shall be two series of bill chapter numbers for each two-year regular session of the Legislature. Bills deposited with the Secretary of State from the beginning of the two-year session through December 31 of the odd-numbered year shall be designated "Statutes of [odd-numbered year], Chapter ____." Bills deposited with the Secretary of State after December 31 of the odd-numbered year shall be designated "Statutes of [even-numbered year], Chapter ____." Concurrent resolutions, joint resolutions, and proposed constitutional amendments adopted by the Legislature shall be chaptered as resolution chapters with a different series of numbers than those assigned to bills but shall otherwise be numbered and designated in the same manner as bills enacted into law.
Ca. Gov. Code § 9510.5