35 ILCS 5/251
For taxable years ending on or after December 31, 2023, if any person earning a credit against the tax imposed under subsections (a) and (b) of Section 201 is a partnership or Subchapter S corporation, the credit is allowed to pass through to the partners and shareholders in accordance with the determination of income and distributive share of income under Sections 702 and 704 and Subchapter S of the Internal Revenue Code, or as otherwise agreed by the partners or shareholders, provided that such agreement shall be executed in writing prior to the due date of the return for the taxable year and meet such other requirements as the Department may establish by rule. Partnership has the meaning prescribed in subdivision (a)(16) of Section 1501.
35 ILCS 5/251