A number appears on the QBI component worksheet that is $30,000 less than my net business income. This is the number that TurboTax uses to start the calculation for the QBI deduction. Why isn't the number to start with my net business income? I can't figure out where or how TurboTax got to that numbe
The QBI deduction calculation has several different parts among its three threshold taxable income levels. At the lowest level (under the threshold of personal taxable income of $157,000 single and $315,000 joint), the QBI is calculated as EITHER 20% of your qualified business income (which is self employed business profit less self employment taxes, self employed health insurance and/or self employed retirement, etc) OR 20% of your personal taxable income less capital gains/dividends.
In TurboTax Home & Business, you can switch to FORMS mode to see the Qualified Business Income worksheets that should specify how the deduction was calculated. Below is a link for how to switch to FORMS mode:
And here is more information on the QBI deduction, including an example of how it is calculated at the different threshold levels: