Cal. Code Regs. tit. 5, § 15283
(a) Expenditures for the following items:
(3) Transporting children within the minimum distance if their number exceeds 1/10 of the number who board a bus beyond that distance. The amount of deductions for those pupils who are in excess of such 1/10 is determined as follows:
Total transportation expense for normal children - (The number of such excess pupils x Transportation cost per normal pupil each year)
(b) Expense of Transportation of Pupils Other than Home-to-School. This deduction is the amount of the actual expense if the actual expense can be readily identified in the district's records.
Otherwise, the deduction is the following amount: The cost per mile for the operation of all buses used to provide pupil transportation (whether for normal or exceptional pupils, as the case may be) multiplied by the number of miles traveled in providing transportation for such pupils other than between home and school.
(c) Depreciation of a school bus due to the travel listed in this subsection (c). The depreciation for each type of travel shall be determined by the following formula wherein “miles” means miles the bus traveled in the fiscal year:
Cost of bus less value of
Miles for a purpose
items required by Section
specified in (1), (2),
15272 to be deducted
X
or (3)
12
Total miles under district ownership
Travel on which depreciation is deducted is community recreation travel pursuant to Education Code Section 39835.
For purposes of approving total transportation expense, there shall be deducted from total current expenses:
1. Amendment of subsection (c) filed 9-23-77; effective thirtieth day thereafter (Register 77, No. 39).