Assembly Bill No. 168
leginfo.legislature.ca.gov
leginfo.legislature.ca.gov
Interestingly, I work for a movie company, where all work is contracted. For directors, screenwriters, stars, etc. It is very traditional to base pay on your "quote" = what you got paid last time. Now they can't ask what the person got paid last time.
Not that it should be any of a company’s business, but if they want that info they can get it. That said many cos. use salary services to inform compensation.
Aggregate salary data, not specific to the individual, remains allowed.
This happened 10/2017 and took effect 01/2018 though—I'm not really sure why it was posted today.
They also prohibited seeking salary information from third parties to affect decisions on whether to hire and for how much.