This seems to be a big deal, though for the life of me, no matter how many times I read the Kitces analysis, I cannot wrap my head around his central thesis/conclusion. In particular, as an S-corp, my ER SEP=IRA or ER solo401K contributions have always been deducted as a business expense before profit flows through, in this case now to QBI. Like in years prior, my contributions now are just as pre-tax as they were historically. For s-corps, profit has always been reduced by ER IRA/401K contributions, the new QBI calculations dont seem to change this, though it may be different for sole props.