Lysondra Ludwig wrote an overview of AB 37 for the Daily Journal New California Laws supplement.

For tax years beginning on or after January 1, 2020 and before January 1, 2025, California’s legal cannabis businesses subject to the state’s personal income tax (i.e. an entity taxed as a pass through) will be able to claim tax deductions or credits on their California state tax return. Read Lysondra's overview, here.

Bill text - AB 37 Personal income taxes: deductions: business expenses: commercial cannabis activity: https://leginfo.legislature.ca.gov/faces/billTextClient.xhtml?bill_id=201920200AB37