There are several pieces to the QBI deduction calculation as it is not a straight 20% of business income. For instance, for
taxable income under the first threshold of taxable income under $157,500 single or $315,000 joint, the calculation is 20% of QBI (which is your qualified business
income less your portion of self-employment taxes, self-employed health
insurance, etc) OR 20% of your taxable income (except capital
gains and dividends), whichever is LESS.
See more information below, including deduction calculation examples within each threshold level: