Ind. Code § 6-3-4-16.5
(a) This section applies to:
(5) Form WH-18 miscellaneous withholding tax statements for nonresidents;
filed with the department after December 31, 2012.
(b) If an employer or any person or entity acting on behalf of an employer files more than twenty-five (25):
(4) Form WH-18 miscellaneous withholding tax statements for nonresidents;
with the department in a calendar year, all forms and Form WH-3 annual withholding tax reports filed with the department in that calendar year by the employer or the person or entity acting on behalf of the employer must be filed in an electronic format specified by the department.
As added by P.L.113-2010, SEC.57. Amended by P.L.137-2012, SEC.59.