There are different components that will be used to determine the QBI deduction, depending upon which is lower. Plus the deduction phases out depending upon the taxpayer's income levels.
Here is more detail:
How is the QBI deduction calculated?
That will depend on
the business owner’s total taxable income,
which includes non-business income (such as wages, interest, capital gains) as
well as business income.
Under $157,500 ($315,000 if filing jointly):
The calculation is straightforward — 20% is applied to QBI or taxable income
minus capital gains and dividends (whichever is less) to come up with the
deduction.
This information is included, along with some examples, in the following FAQ about the 20% Qualified Business Income Deduction:
