California Code, Education Code - EDC § 5208

When outside territory has been annexed to a city for school purposes, the outside territory shall be deemed to be a part of the city for all matters connected with the school department of the city, for the annual levying and collecting of the property tax for the school fund of the city, and for all purposes specified in Chapter 2 (commencing with Section 15100) of Part 10 of this division.

The last assessment roll made by the county assessor shall be the only basis of taxation for the school district on the property outside the corporate limits annexed for school purposes.