2018 qbi deduction

[RWG1950]

Assuming a self-employed taxpayer filing a schedule "C" for 2018 that otherwise qualifies for the 20% QBI subtraction,
would the net "C" business income need to be reduced by 1/2 the SE tax and the SE med. insurance deduction before the 20% calculation ?
Can't seem to find anything relating to this specific issue in chapter #8 of the 2018 TTB.
My newly installed 2019 software does this automatically from the data entry worksheets for the 20% QBI calc, but did not do it last year.
Did the calculation rules change on this for 2019 ?
Thanks for comments.

[New York Enrolled Agent]

My newly installed 2019 software does this automatically from the data entry worksheets for the 20% QBI calc, but did not do it last year.
Did the calculation rules change on this for 2019 ?
Thanks for comments.

It appears your software was not appropriately updated for 2018 tax returns.

The final regulations for §199A were issued on February 1, 2019 and clearly indicate those adjustments must be made to determine the correct amount of qualified business income before applying the 20% calculation.

[ATSMAN]

What is your tax prep software?