Can I take the QBI deduction on a condo unit that I co-own with another person (50%) who will not be using QBI deduction?

[DanielV01]

Yes, it is possible for you to do so.  It can depend on how the income is reported to you.  If it is reported on Schedule K-1, your income may allow you to take the QBI deduction even though your partner has too much income to claim the deduction.  This is because the information necessary to claim QBI is passed through and reported to each partner on Schedule K-1, but the deduction itself is claimed on each one's individual return.  So it is possible for one partner to be able to claim the deduction and for the other partner to not be able to do so.

Here is an FAQ that discusses this topic in greater detail:  https://ttlc.intuit.com/replies/7019998