How it works
The QBI deduction is computed on Form 8995 (simplified) or Form 8995-A (full) and is taken below the line, reducing taxable income but not AGI. The deduction is the lesser of (a) 20% of qualified business income from each qualified trade or business, or (b) 20% of taxable income before the QBI deduction minus net capital gain.
What qualifies
QBI is the net amount of qualified items of income, gain, deduction, and loss from a US trade or business. It excludes capital gains and losses, dividends, interest income not allocable to a business, reasonable compensation paid by an S-corp to its owner, and guaranteed payments from a partnership.
Threshold-based limits
Below the annual taxable income threshold (about $191,950 single / $383,900 joint for 2024), the simplified Form 8995 applies and any qualified business — including SSTBs — gets the full 20%. Above the threshold, W-2 wage and UBIA limits apply, and SSTBs (health, law, accounting, consulting, etc.) phase out completely.
Strategies for owners near the threshold
Bunching deductions, accelerating depreciation, increasing retirement contributions, or making charitable contributions can pull income below the SSTB phase-out threshold and preserve the QBI deduction. The math is sensitive — a single dollar of income can produce a tax cost much greater than $1 once QBI begins to phase out.
Sunset
The QBI deduction (Section 199A) is scheduled to expire for tax years beginning after 2025 unless Congress extends it. Pass-through business owners should assume the deduction is temporary and plan accordingly.
Worked example with numbers
Consider a sole prop with $100,000 in gross receipts and $30,000 in legitimate Schedule C deductions, including this category. Each additional $1,000 of qualifying expense reduces Schedule C net profit by $1,000, which reduces self-employment tax by approximately $1,000 × 92.35% × 15.3% ≈ $141, and reduces income tax by $1,000 × marginal rate. At a 22% federal marginal rate, the combined federal tax savings on each additional $1,000 of legitimate deduction is roughly $361, and state savings sit on top of that. The math is why disciplined categorization throughout the year pays for itself.
Common mistakes that disallow the deduction
The recurring ways this deduction gets disallowed in examination cluster in four categories: (1) personal-use expenses bundled with business (the deduction is disallowed entirely or apportioned downward); (2) inadequate substantiation (no receipt, no invoice, no business-purpose note); (3) the wrong line on Schedule C (not fatal, but it weakens audit defense); and (4) double-counting with another line (for example, deducting an expense on Schedule C and also on Form 8829, or as a personal itemized deduction on Schedule A). The fix in every case is contemporaneous bookkeeping and a clean chart of accounts.