TaxGuyBill
Level 15

After looking at things, I think you are right.  I originally didn't think the Basis limitation would affect QBI, but I think I was wrong.

This FAQ from the IRS isn't directly about this question, but it does provide insight on it (note the section I put in bold) that makes me think you are right, you do need to adjust QBI:

 

A34. The pass-through entity is required to provide the owners QBI information necessary for the owner to compute the deduction. If the entity only has ordinary income from a single trade or business, it may be appropriate to reflect one QBI amount. Some QBI items from a pass-through entity, such as section 1231 gain or loss, may need to be identified separately due to the potential of unique treatment on one or more owners' returns. Items not included in current year taxable income are not included in QBI. Therefore, additional details will also need to be provided for the owners. If for example, in addition to ordinary income the owner is allocated a section 179 deduction, since the 179 deduction may be limited, the detail would be required in order for the owner to properly determine the current year QBI. The instructions for pass-through entity filers include statements that pass-through entities can use when reporting items with respect to the QBID for tax years 2019 and forward.

Also note that the rules to separately state items from each activity for the application of the at-risk rules and passive activity loss limitation rules still apply even when a pass-through entity chooses to aggregate a trade or business for the purposes of section 199A.

https://www.irs.gov/newsroom/tax-cuts-and-jobs-act-provision-11011-section-199a-qualified-business-i...