(1) When the budget amendment is for increased enrollment, the maximum amount of the budget amendment for each fund affected must be determined as follows:
(a) Determine the final budget for the current school fiscal year of each fund affected by the enrollment increase (less any amounts appropriated for capital outlay and any amounts appropriated for addition to the operating reserve) .
(b) Divide the amount determined in (1) (a) by the prior fiscal year enrollment used to calculate budgeted ANB in accordance with 20-9-311 , MCA, and ARM 10.20.102. The resulting per-pupil cost is the maximum permissible per-pupil expenditure for the budget amendment.
(c) Determine the total enrollment increase for the current year in accordance with ARM 10.20.105(1) (a) through (c) . The enrollment count for the current year that will be used to calculate an increase in enrollment will be the October enrollment count as reported to OPI on the fall report or, for petitions received after February 1, the February count reported to OPI on the spring enrollment report.
(d) Multiply the cost per pupil determined in (1) (b) by the enrollment increase determined in (1) (c) . The result is the maximum limitation on a budget amendment for amendments resulting from enrollment increases.
(e) In no case may the district adopt a budget amendment for an enrollment increase that causes the district to exceed the maximum general fund budget as adjusted by the Superintendent of Public Instruction in accordance with 20-9-163 , MCA. The maximum general fund budget will be adjusted as follows:
(i) Determine the enrollment increase for each budget unit within the elementary level or the high school level in accordance with ARM 10.20.105(2) (b) .
(ii) Prorate the total enrollment increase for the current year determined in (1) (c) to each budget unit by multiplying the total enrollment increase by the ratio of the enrollment increase by budget unit determined in (1) (e) (i) to the total enrollment increase determined in (1) (c) . Round the result of the calculation to the nearest hundredth (.xx) .
(iii) Determine the current year's adjusted ANB used to adjust the maximum general fund budget for each budget unit by:
(A) summing the prior year enrollment as defined in ARM 10.20.105(1) (b) by budget unit and the enrollment increase by budget unit as calculated in (1) (e) (ii) ;
(B) multiplying the sum in (1) (e) (iii) (A) by the total of PI days and PIR days approved for the current year, and dividing the total by 180; and
(C) rounding the ANB up to the nearest whole number.
(iv) Calculate the basic entitlement and total per-ANB entitlement using the adjusted ANB as calculated in (1) (e) (iii) (C) .
(v) Subtract the basic entitlement and total per-ANB entitlement calculated using the ANB based on the prior year average enrollment from the basic entitlement and total per-ANB entitlement calculated in (1) (e) (iv) .
(vi) Determine the adjusted maximum general fund budget by adding the amount calculated in (1) (e) (v) to the current year maximum general fund budget reported on the budget form for the current fiscal year.
(2) For budget amendments other than those due to enrollment increases, the budget amendment is limited to the expenditures considered by the trustees to be reasonable and necessary to finance the conditions of the budget amendment. The budget amendment must include an expenditure detail.