Cal. Rev. & Tax. Code § 2703

The entire tax on the secured roll may be paid when the first half is due. The first half may be paid separately when the first half is due or at any time thereafter until the properties on the current roll become tax defaulted. The second half may be paid separately only if the first half has been paid. The tax collector shall accept payment of current year taxes even though prior year delinquencies on the real property may exist. The acceptance of that payment shall not affect the validity of any sale in satisfaction of a lien for defaulted taxes.