Regarding sec 179 or bonus depreciation, anything that's allowable in the current year should generally also be applied to QBI. Since anything allowable in the current year is already in net income of Sch C, and that's the starting point for QBI, you shouldn't need any further adjustments. Unless I'm still not understanding the scenario.

K-1s are a little more complicated b/c of ambiguity in IRS instructions regarding what should be included in the box 17/20 (depending on whether 1120S or 1065 k1) QBI amount. You'll just have to look closely at the K-1 and supporting statements to see how the preparer calculated the QBI amount. If the QBI amount in box 17/20 has already subtracted items like section 179, then you don't need to make further adjustments. (Except in the rare case where the k1 already subtracted 179 expenses, but they're not allowed at the individual level, in which case you'll want to add disallowed 179 expenses back to the QBI amount in box 17/20.) If the box 17/20 QBI amount has NOT accounted for those separately stated items, then you'll need to make entries in the QBI Deduction Info wksht, line E, to account for those items to the extent they're connected to QBI.