Answer:
$14,400
Explanation:
QBI deduction can be as much as 20% of QBI but it cannot exceed 20% of taxable income before QBI deduction and/or capital gains.
QBI deduction also starts to phase out if the couple's income is higher than $321,400 (for 2019).
phase out = 1 - [($381,400 - $321,400) / $100,000] = 1 - 0.6 = 40%
we must choose the higher between:
tentative QBI deduction based on W-2 wages = 50% x $40,000 x 40% = $8,000
or
QBI deduction based on capital investment limit = (25% x $40,000 x 40%) + $0 (no qualified property) = $4,000
allowable QBI deduction:
($300,000 x 20% x 40%) - {[($300,000 x 20% x 40%) - $8,000] x (1 - 40%)} = $24,000 - [($24,000 - $8,000) x 0.60] = $24,000 - $9,600 = $14,400