Returns with respect to the income tax herein imposed shall be in such form as the department may prescribe. Returns shall be filed with the department on or before the fifteenth day of the fourth month following the close of the accounting period of the association.
S.C. Code § 12-13-80
2016 Act No. 160, Section 4.E, provides as follows:
"E. This SECTION takes effect upon approval by the Governor and first applies to tax years beginning after 2015."