States use four basic systems to regulate rates:
Prior approval: the insurer files and must wait for approval before using the rate.
File and use: the insurer files the rate and may start using it right away.
Use and file: the insurer uses the rate first and files it afterward.
Open competition: no filing; the market sets rates.
California uses prior approval for most property and casualty insurance (§1861.05). The insurer files a complete rate application, the Commissioner gives public notice, and the application is deemed approved 60 days after that notice unless a hearing applies. No rate may be approved or remain in effect if it is excessive, inadequate or unfairly discriminatory. The degree of competition in the market is not considered.
Reading the Code (§16): "shall" is mandatory and "may" is permissive, unless the context shows otherwise.
Notice by mail (§38): unless the Code provides otherwise, a notice may be given by mailing it, postage prepaid, to the person's residence or principal place of business in California. The affidavit of the person who mailed it is prima facie evidence that it was mailed. Certified mail and a return receipt are not required.