Responses to your questions:
1) If the composite tax is reflected on the 2017 Indiana K-1 line 8, then this is treated as 2017 withholding on the Indiana IT-40.
2) If the pass-through entity did not treat the composite tax as a distribution, then it is not an itemized deduction as the individual did not pay it, the entity did.
*A reminder that posts in a forum such as this do not constitute tax advice.
Also keep in mind the date of replies, as tax law changes.
