The qualified business income deduction under IRC §199A allows eligible taxpayers to deduct up to 20% of qualified business income from pass-through entities and sole proprietorships. OBBBA made it permanent. But the deduction is heavily limited for high-income taxpayers by the W-2 wage limitation, the UBIA of qualified property alternative, and the complete phaseout for specified service trades or businesses above the income threshold. The mechanics matter enormously - a 20% deduction at the 37% bracket saves $0.074 on every dollar of QBI. Getting it wrong in either direction is expensive.
TCJA's §199A was originally set to expire after 2025. OBBBA (P.L. 119-21) made it permanent with no sunset. The income thresholds and phase-in ranges continue to be inflation-adjusted annually. For 2026, the threshold is approximately $201,750 (single) / $403,500 (MFJ) - above which the W-2 wage limitation begins to apply and SSTB income begins to phase out.
For taxpayers with taxable income below the threshold, the QBI deduction is simply 20% of qualified business income, subject to an overall cap of 20% of (taxable income minus net capital gains). No W-2 wage analysis is needed below the threshold.
For taxpayers above the threshold, the deduction is additionally limited to the greater of two W-2/UBIA tests computed at the trade or business level:
The W-2 wage limitation is fully phased in above the threshold. Between the threshold and $100,000 above it ($50,000 for single filers), the limitation is partially applied using a phase-in formula.
W-2 wages for §199A purposes are wages paid by the trade or business that are properly allocable to QBI. This includes wages paid to employees (W-2 box 1), elective deferrals, and deferred compensation (certain amounts from W-2 boxes 12). It does not include guaranteed payments to partners, payments to independent contractors reported on 1099s, or reasonable compensation paid by an S-corporation to its owner-employee (that is a deduction against QBI, not a W-2 wage for purposes of the limitation calculation - though it does appear on a W-2).
UBIA is the cost basis of qualified property at the time it was placed in service by the business - not the depreciated book or tax basis. Qualified property is tangible property subject to depreciation that is held by the trade or business at the close of the tax year and used in the production of QBI. The 2.5% UBIA factor in Test 2 allows capital-intensive businesses (real estate, manufacturing) with large asset bases but potentially lower W-2 wage bills to access a larger deduction than Test 1 alone would allow.
The §199A deduction phases out entirely for income from specified service trades or businesses (SSTBs) once taxable income exceeds the threshold plus $100,000 (MFJ) / $50,000 (single). Above the complete phaseout, SSTB income produces zero QBI deduction regardless of W-2 wages or UBIA.
SSTBs include: health, law, accounting, actuarial science, performing arts, consulting, athletics, financial services, brokerage services, investing and investment management, trading, and dealing in securities. It also includes "any trade or business where the principal asset of such trade or business is the reputation or skill of one or more of its employees or owners" - a catch-all that has generated significant controversy and regulatory clarification.
Notably excluded from SSTB status: engineering, architecture, real estate (including REITs and rental activities), insurance, banking, lending, and most trades or businesses that sell products rather than services. A physician who also owns the real estate where the practice operates can separate the real estate activity and potentially claim QBI on the real estate income even if the medical practice is an SSTB phased out.
Under Treas. Reg. §1.199A-4, a taxpayer can elect to aggregate multiple trades or businesses for purposes of the W-2 wage limitation and the overall QBI calculation, treating them as a single trade or business. Aggregation can be beneficial when one business has high QBI but low W-2 wages (limited by the wage test) and another business has high W-2 wages but lower QBI (surplus wages that would otherwise be wasted).
Requirements for aggregation: the businesses must share 50% or more common ownership, must have the same tax year, and must satisfy at least two of three integration factors (same customers, same employees/facilities, same products/services/production processes). The aggregation election must be made on the return for the year it first applies and must be consistently applied going forward.
S-corporation reasonable compensation optimization. Owner-employee wages reduce QBI (wages are deducted from business income before the QBI calculation) but increase the W-2 wage pool for the limitation test. The optimal salary balances SE tax savings against the impact on QBI and the W-2 limitation. This is not a simple calculation - model it explicitly before year-end.
SSTB entity separation. A business that performs both SSTB and non-SSTB activities can potentially separate them into distinct entities, allowing the non-SSTB income to qualify for the deduction. The IRS has anti-fragmentation rules under Treas. Reg. §1.199A-5(c)(2) that apply when an SSTB and a non-SSTB have 50%+ common ownership and share expenses - the non-SSTB is also treated as an SSTB if it provides 80%+ of its services to the SSTB.
Qualified REIT dividends and PTP income. REIT dividends and qualified publicly traded partnership (PTP) income are separately eligible for the 20% deduction without regard to W-2 wages or UBIA - and without SSTB restrictions. For high-income taxpayers completely phased out of the pass-through deduction, shifting investment toward REIT shares can restore some §199A benefit.