26 CFR § 1.1382-4
Taxable income of cooperatives; payment period for each taxable year
June 25, 2020
The payment period for a taxable year is the period beginning with the first day of such taxable year and ending with the fifteenth day of the ninth month following the close of such year.
[T.D. 6643, 28 FR 3156, Nov. 26, 1963]