(a) Space is considered to be over-allocated if (1) the charter school's actual in-district classroom ADA is less than the projected in-district classroom ADA upon which the facility allocation was based and (2) the difference is greater than or equal to a threshold ADA amount of 25 ADA or 10 percent of projected in-district classroom ADA, whichever is greater. The per-pupil rate for over-allocated space shall be equal to the statewide average cost avoided per pupil set pursuant to Education Code section 42263 for 2005-06, adjusted annually thereafter by the CDE by the annual percentage change in the general-purpose entitlement to charter schools calculated pursuant to Education Code section 47633, rounded to the next highest dollar, and posted on the CDE Web site. The reimbursement amount owed by the charter school for over-allocated space shall be equal to (1) this rate times the difference between the charter school's actual in-district classroom ADA and the projected in-district classroom ADA upon which the facility allocation was based, less (2) this rate times one-half the threshold ADA. For purposes of this subdivision, the actual in-district classroom ADA shall be determined using the report submitted pursuant to section 11969.9(l) in conjunction with the second principal apportionment under Education Code section 41601.

(b) A charter school must notify the school district when it anticipates that it will have over-allocated space that could be used by the school district. Upon notification by a charter school that the charter school anticipates having over-allocated space, a school district may elect to use the space for school district programs. The school district must notify the charter school whether or not it intends to use the over-allocated space within 30 days of the notification by the charter school. If the school district notifies the charter school that it intends to use all or a portion of the over-allocated space, payments for over-allocated space and pro rata share payments shall be reduced accordingly beginning at the time of the school district notification to use the space. If the school district notifies the charter school that it does not intend to use the space, the charter school must continue to make payments for over-allocated space and pro rata share payments. The school district may, at its sole discretion, reduce the amounts owed by the charter school.

(c) With respect to charter schools established at existing public school sites pursuant to Education Code sections 47605(a)(2), 52055.5, 52055.55, or 52055.650, the provisions of this section are limited by the applicable provisions of subdivisions (c) and (d) of section 11969.3.