A portion of a school district that is taxed through a general obligation (G.O.) bond based on the value of the property and approved by the voters in that portion of the district being taxed. When SFIDs were created in 1998, they required two-thirds voter approval. In July 2001, the Legislature added the option of a 55% voter approval threshold with the additional accountability provisions of Proposition 39. Typically, SFIDs involve new housing developments that create additional facility needs for the school district.