Shouldn't QBI be reduced by Sec 179 depreciation on a pass through entity. It is not happening with an S Corporation on the partners K-1?

I thought this through again and still believe that charitable contributions would not be consider a QBI item attributable to a trade or business.

There is no question that it is a flow-through from the S-corp and would otherwise be deductible, subject to limitations, to the corporation in computing its taxable income had it not been an S-corp.  However, if we were to refer to §1366(b) and §1.1366-1(b), it is clearly stipulated that "the character of any item... is determined for the S corporation and retains that character in the hands of the shareholder."

It is accepted and recognized that the mere existence of an S-corp does not automatically equate to the operation of a trade or business.  For example, an S-corp could be engaged in rental activities and the rental income passed through to the shareholder(s) must still be characterized as passive income subject to §469 unless those activities rise to the level of §162 trade or business.  It is, therefore, entirely possible that an s-corp item is not attributable to a trade or business.

In determining the amount deductible for charitable contributions and gifts, §162, which governs deductions for trade or business expenses, does not refer to §170 just for the limitation but specifically ***excepted*** charitable contributions and gifts from subsection (a).  In contrast, §179(b)(3) stipulates that "the amount allowed as a deduction... shall not exceed the aggregate amount of taxable income of the taxpayer for such taxable year which is derived from the active conduct by the taxpayer of any ***trade or business*** during such taxable year."

In conclusion, IMHO, we should differentiate the treatment of charitable contributions flowing through from an S-corp, as being an item not attributable to a trade or business, from §179 allowed which retains the character of being a trade or business expense and, therefore, constitute a QBI item.