What is Qualified Business Income Deduction? I have an S corp and 20% of my K-1 is a lot, but my QBI deduction is only $30. Isnt it supposed to be a direct 20% of K-1?

There is a decent summary on the IRS web site at the link below.

https://www.irs.gov/newsroom/qualified-business-income-deduction

Does your K-1 have a code Z in box 20 ? 

And TT has worksheets for everything ... save a PDF with the worksheets to see how the QBI is being calculated ...

• click in the left menu column on TAX TOOLS, then PRINT CENTER.
• Then choose "Print, save, view this year's return."
• The next screen should offer some options:  "Just my tax returns", or "include government worksheets (optional)", or "include government and TurboTax worksheets (optional.)"
• See if one of those PDFs has what you need.  The latter has the most pages.

Or a code V in Box 17 for an S corporation (K-1 1120-S).

you may also want to review form 8995/8995-A which is the IRS form for computing the overall QBI deduction once QBI for each trade or business id calculated from the separate worksheets.  

One thing I found was my QBI credit was not as much as I thought it would be.  Because I had a business loss the prior year and it carried it over and took it into account.