Section 202.5

(35 ILCS 5/202.5) Sec. 202.5. Net income attributable to the period beginning prior to the first day of a month and ending after the last day of the preceding month. (a) In general. With respect to the taxable year of a taxpayer beginning prior to the first day of a month and ending after the last day of the preceding month, net income for the period after the last day of the preceding month, is that amount that bears the same ratio to the taxpayer's net income for the entire taxable year as the number of days in that taxable year after the last day of the preceding month bears to the total number of days in that taxable year, and the net income for the period prior to the first day of the month is that amount that bears the same ratio to the taxpayer's net income for the entire taxable year as the number of days in that taxable year prior to the first day of the month bears to the total number of days in that taxable year. (b) Election to attribute income and deduction items specifically to the respective portions of a taxable year prior to the first day of a month and ending after the last day of the preceding month. In the case of a taxpayer with a taxable year beginning prior to the first day of a month and ending after the last day of the preceding month, the taxpayer may elect, instead of the procedure established in subsection (a) of this Section, to determine net income on a specific accounting basis for the 2 portions of the taxable year: (1) from the beginning of the taxable year through the last day of that apportionment