Cal. Rev. & Tax. Code § 3693

(a) With the exception of the sealed bid sale procedures authorized under Section 3692, all sales pursuant to this chapter shall be at public auction to the highest bidder. The amount of the high bid shall be paid by any method of payment authorized by Section 2502, 2503.2, or 2504, which method is at the discretion of the tax collector. Unless otherwise specified by the tax collector, payment is due on or before the close of auction.
(b) The tax collector may require a person to submit a deposit, by any method of payment authorized by Section 2502, 2503.2, or 2504, for the purposes specified in this subdivision. A tax collector requiring a deposit pursuant to Section 3693.1 may determine, and shall provide public notice before the date of the sale upon determining, all of the following:
1. (1) The method of payment of this deposit.
2. (2) The amount of this deposit.
3. (3) The due date of this deposit.
4. (4) Whether the deposit will be applied for one or more of the following purposes:
  1. (A) As a condition to submitting a bid on property that is being sold under this chapter.
  2. (B) As a payment toward specified property that is being sold under this chapter. If a deposit is applied for this purpose, the deposit may be applied as payment toward more than one specified property based upon the amount of the minimum bid for each property.
(c) This section shall become operative on January 1, 2029.