Section 199A QBI Deduction: The Complete Guide for Small Business Owners

By Yarik Yarosh, CPA ·September 5, 2026 ·8 min read

Written by Yarik Yarosh, CPA (US & Canada) September 5, 2026 · FL CPA license AC61704 · CPA Ontario

The Section 199A qualified business income (QBI) deduction is the most significant tax benefit available to pass-through business owners (sole proprietors, S-Corp shareholders, partners, LLC members). It provides a deduction of up to 20% of qualified business income, effectively reducing the tax rate on business income by approximately 20%. However, the deduction has multiple limitations that depend on taxable income, whether the business is a specified service trade or business (SSTB), W-2 wages paid, and the unadjusted basis of qualified property.

✓Key takeaway

QBI deduction framework:

Below the income threshold ($191,950 single / $383,900 MFJ in 2025):

The deduction is 20% of QBI, regardless of SSTB status, W-2 wages, or UBIA
Simplest calculation: 20% x net business income
The deduction cannot exceed 20% of taxable income (before the QBI deduction)

Between the threshold and the upper limit ($266,950 single / $533,900 MFJ, widened by OBBBA):

For SSTBs: the deduction phases out linearly to $0 at the upper limit
For non-SSTBs: the W-2 wages/UBIA limitation begins to phase in

Above the upper limit:

For SSTBs: the QBI deduction is $0 (completely phased out)
For non-SSTBs: 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 + 2.5% of the unadjusted basis immediately after acquisition (UBIA) of qualified property

Who qualifies:

Sole proprietors (Schedule C income)
S-Corp shareholders (K-1 income, not W-2 salary)
Partners in partnerships (K-1 income, including guaranteed payments in some cases)
LLC members (depending on how the LLC is taxed)
REIT dividends and publicly traded partnership income also qualify

What is QBI?

Net income from a qualified trade or business
Includes: Schedule C income, S-Corp K-1 income, partnership K-1 income
Excludes: W-2 wages, capital gains/losses, interest income (unless business-related), guaranteed payments from partnerships, reasonable compensation from S-Corps

What is NOT QBI:

Reasonable compensation (W-2 salary from an S-Corp)
Guaranteed payments to a partner
Investment income (interest, dividends, capital gains)
Income from a specified agricultural or horticultural cooperative (special rules apply)

SSTB categories (IRC 199A(d)(2)): Health care, law, accounting, actuarial science, performing arts, consulting, athletics, financial services, brokerage services, and any trade or business where the principal asset is the reputation or skill of its employees or owners.

How is QBI calculated?

QBI is the net profit from a qualified trade or business, calculated as: gross income from the business, minus deductions allocable to the business (including the deductible portion of self-employment tax, self-employed health insurance, and retirement plan contributions for sole proprietors). For current guidance, see IRS QBI deduction FAQ. For S-Corp shareholders, QBI is the shareholder’s share of the S-Corp’s ordinary business income (the K-1 Box 1 amount), NOT including the W-2 salary (which is a deduction to the S-Corp, not QBI).

How does the QBI deduction interact with S-Corp salary?

Hypothetical example

Round numbers. A plumbing S-Corp. Net income before owner salary: $200,000. Plumbing is NOT an SSTB. Owner’s total taxable income will be below $266,950 (single), so no W-2 wage or UBIA limitation applies.

Scenario A: Owner salary $60,000.

K-1: $200,000 - $60,000 - $4,590 (employer FICA) = $135,410
QBI deduction: 20% x $135,410 = $27,082
Tax savings from QBI: $27,082 x 24% = $6,500

Scenario B: Owner salary $90,000.

K-1: $200,000 - $90,000 - $6,885 (employer FICA) = $103,115
QBI deduction: 20% x $103,115 = $20,623
Tax savings from QBI: $20,623 x 24% = $4,950
QBI lost by raising salary: ($27,082 - $20,623) = $6,459
Tax cost of lost QBI: $6,459 x 24% = $1,550

Scenario C: Owner salary $120,000.

K-1: $200,000 - $120,000 - $9,180 (employer FICA) = $70,820
QBI deduction: 20% x $70,820 = $14,164
Tax savings from QBI: $14,164 x 24% = $3,400
QBI lost by raising salary (from Scenario A): ($27,082 - $14,164) = $12,918
Tax cost of lost QBI: $12,918 x 24% = $3,100

The QBI trade-off: Every dollar shifted from K-1 to salary LOSES 20% x marginal rate in QBI benefit AND GAINS 7.65% employer FICA exemption. At a 24% marginal rate:

QBI benefit per K-1 dollar: 20% x 24% = 4.8%
FICA cost per salary dollar: 7.65% (employer) + 7.65% (employee) = 15.3%
Net benefit of shifting $1 from salary to K-1: 15.3% - 4.8% = 10.5%

This confirms that the S-Corp FICA savings ALWAYS exceed the QBI reduction for non-SSTB businesses. The optimal salary is the minimum that qualifies as “reasonable,” not a number calculated to maximize QBI.

SSTB example (consulting firm): Same $200,000 net income, but the business IS an SSTB. Owner’s taxable income is $280,000 (single), which is within the phase-out range ($266,950-$316,950).

Applicable percentage: ($316,950 - $280,000) / $50,000 = 73.9%
QBI before phase-out: $135,410 (from Scenario A)
QBI allowed: $135,410 x 73.9% = $100,068
QBI deduction: 20% x $100,068 = $20,014

If the owner’s income were $320,000 (above $316,950): QBI deduction = $0. The SSTB owner gets NO benefit from QBI and should focus entirely on minimizing total tax through salary optimization, retirement contributions, and other deductions.

Planning strategies to stay below the SSTB threshold:

Maximize retirement contributions ($23,500 deferral + employer match/profit sharing)
Maximize the accountable plan reimbursements (home office, mileage)
Defer income to the next year if near the threshold
Use a SEP or defined benefit plan to reduce AGI below the threshold

Illustrative numbers only, not a real client and not advice for your facts.

How do the limitations work at higher incomes?

Hypothetical example

Round numbers. Three business owners, each with $300,000 in taxable income (single filer), operating different types of businesses:

Owner A: Consulting firm (SSTB), S-Corp, $300,000 QBI

Above upper threshold ($266,950)
SSTB: QBI deduction = $0
No deduction available. All QBI taxed at ordinary rates.

Owner B: Marketing agency (NOT SSTB), S-Corp, $300,000 QBI, $80,000 in W-2 wages (owner salary)

Above upper threshold
Non-SSTB: deduction limited to greater of:
- (a) 50% of W-2 wages: $80,000 x 50% = $40,000
- (b) 25% of W-2 wages + 2.5% of UBIA: ($80,000 x 25%) + ($30,000 x 2.5%) = $20,000 + $750 = $20,750
Greater of $40,000 or $20,750 = $40,000
20% of QBI: $300,000 x 20% = $60,000
Deduction: lesser of $60,000 or $40,000 = $40,000
Tax savings: $40,000 x 35% = $14,000

Owner C: Construction company (NOT SSTB), S-Corp, $300,000 QBI, $80,000 W-2 owner salary + $120,000 employee wages, $500,000 UBIA in equipment

Above upper threshold
Non-SSTB: deduction limited to greater of:
- (a) 50% of W-2 wages ($200,000): $100,000
- (b) 25% of W-2 wages + 2.5% of UBIA: ($200,000 x 25%) + ($500,000 x 2.5%) = $50,000 + $12,500 = $62,500
Greater of $100,000 or $62,500 = $100,000
20% of QBI: $60,000
Deduction: lesser of $60,000 or $100,000 = $60,000 (full 20%)
Tax savings: $60,000 x 35% = $21,000

The construction company owner gets the full 20% deduction because W-2 wages paid to employees create a high enough floor. The marketing agency owner gets a partial deduction. The consultant gets nothing because consulting is an SSTB.

If Owner C’s construction company had used subcontractors instead of employees (no employees, just the $80,000 owner W-2 wage), the W-2 wages test would drop to 50% x $80,000 = $40,000, cutting the deduction from $60,000 to $40,000, a $20,000 reduction. This is why capital-intensive or labor-heavy businesses that classify workers as W-2 employees (rather than 1099 subcontractors) generally preserve more QBI deduction above the threshold.

Illustrative numbers only, not a real client and not advice for your facts.

Related guides:

How do specified service trades or businesses affect your QBI deduction?

Specified service trades or businesses (SSTBs) including law, medicine, accounting, consulting, financial services, and performing arts face a phase-out of the QBI deduction at higher income levels. For 2025, the QBI deduction phases out for SSTBs between $191,950 and $241,950 for single filers and $383,900 and $483,900 for joint filers, with zero deduction above the upper threshold. Non-SSTB businesses above the income threshold are limited to the greater of 50% of W-2 wages or 25% of W-2 wages plus 2.5% of the unadjusted basis of qualified property, but they never lose the deduction entirely. The SSTB classification looks at the principal asset of the business, so if more than 10% of gross receipts come from specified service activities (5% for businesses with over $25 million in gross receipts), the entire business is treated as an SSTB.

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Cite this page

Yarik Yarosh, CPA. "Section 199A QBI Deduction: The Complete Guide for Small Business Owners." Blue Cloud CPA, September 5, 2026. https://bluecloudcpa.com/guides/small-business-section-199a-qbi-complete-guide

This guide is general information, not tax advice for your specific situation. Which points apply, and how, depends on your facts.