Per IRS Instructions for Form 1040, page 6:
Qualified business income deduction. Beginning in 2018, you may be able to deduct up to 20% of your qualified business income from your qualified trade or business, plus 20% of your qualified REIT dividends and qualified PTP income. The deduction can be taken in addition to your standard deduction or itemized deductions.
For more information, see the instructions for line 9 and Pub. 535.
To complete the Qualified business income (QBI) section for self-employed or sole proprietor income in TaxAct: