Indiana Code Title 6. Taxation § 6-3-4.5-14

(1) three (3) years after the due date of the partnership's return, including any valid extension granted under IC 6-8.1-6-1;

(2) three (3) years after the date the partnership's return is filed with the department;

(3) in the case of the partnership's underreporting of its adjusted gross income by more than twenty-five percent (25%), the periods provided in subdivisions (1) and (2) shall be six (6) years;

(4) if the partnership fails to file a return required under IC 6-3-4-10, files a fraudulent return, or files a substantially blank return, no time limit;

(5) in the case of a report of proposed partnership adjustments arising from final federal adjustments:

whichever is later;  or

(6) in the case of a report of proposed partnership adjustments issued to a tiered partner that is a partnership as a direct or indirect result of another partnership's report of final partnership adjustments, final federal adjustments, or an amended return, one hundred eighty (180) days after the applicable deadline for the tiered partner or the date otherwise determined under this section for the partnership, whichever is later.