California employers can no longer ask job applicants about their prior salary and -- if applicants ask -- must give them a pay range for the job they are seeking, under a new state law that takes effect Jan. 1. AB168, signed Thursday by Gov. Jerry Brown, applies to all public- and private-sector California employers of any size. The goal is to narrow the gender wage gap. If a woman is paid less than a man doing the same job and a new employer bases her pay on her prior salary, gender discrimination can be perpetuated, the bill's backers say. Last year, the state passed a weaker law that said prior compensation, by itself, cannot justify any disparity in compensation. The new bill goes further by prohibiting employers, "orally or in writing, personally or through an agent," from asking about an applicant's previous pay. However, if the applicant "voluntarily and without prompting" provides this information, the employer may use it "in determining the salary for that applicant."