Cal. Gov. Code § 16521

To be eligible to receive and retain demand or time deposits, a bank shall deposit with the Treasurer as security for such deposits, securities specified in Section 16522, and approved by the Treasurer, in an amount in value at least 10 percent in excess of the amount deposited with the bank. Uncollected funds shall be excluded from the amount deposited in a demand account with a bank when determining the security requirements for such deposits.