The Basic Mechanics
QBI is qualified business income from a pass-through entity: sole proprietorship (Schedule C), partnership, S-corporation, or some LLCs. It does NOT include W-2 wages, capital gains, dividends, or interest income.
The basic deduction is the lesser of: (a) 20% of QBI, or (b) 20% of (taxable income minus net capital gains). The taxable income limitation prevents the QBI deduction from being so large that it eliminates regular income tax entirely.
Below the income thresholds — $200,000 single / $400,000 MFJ for 2026 — the calculation is straightforward. Take 20% of net QBI, that's your deduction. No SSTB rules, no wage/property test. Most freelancers never deal with the complex parts.
Above the thresholds, the rules become complex. Specified Service Trades or Businesses (SSTBs) start phasing out the deduction, fully eliminating it $50K above the threshold ($250K single / $500K MFJ). Non-SSTB businesses face a wage and qualified property test that limits the deduction.
What Counts as Qualified Business Income
QBI = net domestic business income from qualified trade or business. It includes: profit from sole proprietorships (Schedule C), share of partnership ordinary business income (K-1), share of S-corp ordinary income (K-1), and rental real estate income that rises to the level of a trade or business.
QBI does NOT include: W-2 wages from your S-corp paid to yourself (those are subject to FICA, not QBI), guaranteed payments to partners, reasonable compensation, capital gains, dividends from C-corps, interest income, foreign business income, or income from real estate that's not a trade or business.
The 'reasonable compensation' carve-out for S-corps creates an interesting tension. Lower W-2 wages mean more QBI (which gets the 20% deduction). But unreasonably low wages risk IRS reclassification. The optimal balance: pay defensible wages and let the rest flow as QBI for the 199A deduction.
Rental real estate qualifies as QBI only if it constitutes a 'trade or business.' The IRS issued Rev. Proc. 2019-38 providing a safe harbor: 250+ hours of rental services per year, separate books and records, contemporaneous logs of services. Casual landlords with one property typically don't qualify; active operators with multiple properties usually do.
Specified Service Trades or Businesses (SSTBs)
SSTBs are specifically defined as businesses where the principal asset is the reputation or skill of one or more employees: health, law, accounting, actuarial science, performing arts, consulting, athletics, financial services, brokerage services, or any business where the principal asset is reputation/skill.
Common SSTB examples: doctors, lawyers, accountants, financial advisors, consultants, actors, athletes, investment managers. Common non-SSTB examples: software development, graphic design, engineering, manufacturing, real estate, restaurants, retail.
Engineers and architects were specifically EXCLUDED from SSTB status (they would otherwise have qualified). This is a unique carve-out in the statute — engineers and architects are non-SSTBs even though their businesses depend on professional reputation/skill.
Below the threshold ($200K/$400K), SSTB classification doesn't matter. You get the 20% deduction either way. Above the threshold and through the phase-out range ($200K-$250K single, $400K-$500K MFJ), SSTBs get a partial deduction. Above $250K/$500K, SSTBs get NO deduction.
Strategic implication for SSTBs above the threshold: managing taxable income to stay in the phase-out range or below is valuable. Maxing 401(k) and HSA contributions, accelerating deductions, and timing income across years can preserve QBI eligibility.
The Wage and Property Test for Non-SSTBs
Non-SSTB businesses above the threshold face a different limitation: the deduction is the lesser of 20% of QBI OR the greater of (a) 50% of W-2 wages paid by the business, or (b) 25% of W-2 wages plus 2.5% of unadjusted basis of qualified property.
This test is designed to limit the QBI deduction to businesses with real economic substance — businesses that pay wages and own depreciable property. A passive consulting business with no employees and no property might fail the test even if technically non-SSTB.
Concrete example: $500K of QBI, $0 W-2 wages, $0 qualified property. Standard QBI calculation: $100K deduction (20%). But the wage/property test caps at $0 (greater of 50% × 0 or 25% × 0 + 2.5% × 0). Deduction is the lesser: $0. Above the threshold, this business gets no QBI deduction.
The fix: pay W-2 wages. If you elect S-corp status and pay yourself $80K of W-2 wages, the wage test now allows $40K of QBI deduction (50% × $80K). The trade-off: those wages are subject to FICA (15.3%), so you're paying $12,240 of FICA to enable $40K of QBI deduction (worth maybe $14,000 at 35% bracket). Net positive — but make sure to run the actual math.
Common Strategies to Maximize 199A
Income management to stay below the threshold. If you're an SSTB earning $220K (above $200K single threshold), your QBI is partially phased out. Maxing 401(k) and HSA contributions to drop taxable income below $200K could preserve the full deduction.
S-corp election for non-SSTBs above the threshold. Paying yourself W-2 wages enables the wage test to be met, unlocking QBI deduction that would otherwise be limited. The FICA cost is offset by the QBI tax savings.
Aggregating businesses. Multiple businesses you own can be aggregated under Section 199A's aggregation rules, potentially allowing wages or property from one business to support QBI deduction in another. This is mechanical and requires careful documentation.
Real estate trade-or-business qualification. Rental income generally doesn't get QBI, but operations that meet the trade-or-business standard do. Reviewing your activity level, documentation, and structure can convert non-QBI rental income into QBI.
Year-end income deferral. If you're an SSTB about to cross the phase-out, accept payments in January instead of December. Conversely, if you're below the threshold and can absorb more income, accept early.
Charitable bunching. The QBI deduction is computed before charitable deductions, but those charitable deductions can lower taxable income enough to keep you in different QBI brackets. Coordinating charitable giving with QBI strategy can compound benefits.
When 199A Doesn't Apply
C-corporations: do not get QBI deduction. The 199A deduction only applies to pass-through entities. C-corps get the 21% corporate tax rate but face double taxation on dividends.
W-2 wages: regardless of who pays them, W-2 wages are not QBI. Even if the business owner pays themselves wages from their S-corp, those wages are not QBI for the owner.
REIT dividends and PTP income: have their own 20% deduction under separate rules. Treated similarly to QBI but mechanically different.
Investment income: dividends from C-corps, interest, capital gains — none qualifies as QBI.
Foreign business income: only domestic business income qualifies. International income is excluded.
Sunset risk: Section 199A is currently scheduled to expire after the 2025 tax year, but legislative extensions have kept it through 2026. Long-term direction is uncertain. Plan for QBI being available in 2026 but recognize that future years are uncertain.