California Code, Streets and Highways Code - SHC § 10312

(a) When, upon the hearing, the proposed assessment provided for in subdivisions (d) and (e) of Section 10204, and the maximum annual assessment provided for in subdivision (f) of that section, are confirmed as filed, as modified, or corrected, by resolution, the legislative body shall order the proposed improvement to be made or acquired, and declare its action upon the report and assessment. The resolution shall be final as to all persons, and the assessment thereby levied upon the respective subdivisions of land in the assessment district.

(b) If an annual assessment to pay for administrative cost is provided for pursuant to subdivision (a), the legislative body shall determine, by resolution, the amount of the annual assessment for this purpose, which shall not exceed the maximum assessment provided for in subdivision (a) and shall not exceed a reasonable estimate of costs actually incurred or likely to be incurred. This determination may be included in the resolution adopted pursuant to subdivision (a). The legislative body may subsequently determine by resolution that the annual assessment shall be a different amount, but in no event shall the annual assessment exceed the maximum annual assessment provided for in subdivision (a). Resolutions adopted pursuant to this subdivision shall be final as to all persons, and the annual assessment in the amount determined shall thereby be levied annually until changed by resolution adopted pursuant to this section. These assessments may be collected in the same manner and in the same installments as the assessments levied pursuant to subdivision (a), and may be combined with those assessments for collection in any manner which is convenient and economical.