There shall be included in each budget an appropriation for "reserve for uncollected taxes" sufficient in amount so that the anticipated cash receipts for the fiscal year shall at least equal the sum of the following items, each of which is hereinafter referred to as a "lawful yearly expenditure" :
In the event that the exact amount of any such lawful yearly expenditure shall not be known at the time of the adoption of the budget, the amount thereof shall be estimated, but no such estimate shall be less than the amount of such lawful yearly expenditure for the next preceding fiscal year; provided, however, that in the case of a Type II school district, the lawful yearly expenditure for the amount due or to become due for school taxes prior to the end of the fiscal year shall be based upon the proposed budget submitted by the local board of education to the commissioner pursuant to section 28 of P.L. 1975, c. 212 (C. 18A:7A-28).
N.J.S. § 40A:4-40