IRC 199A Qualified Business Income Deduction: Complete Guide to the 20% Pass-Through Deduction

By Yarik Yarosh, CPA ·September 5, 2026 ·7 min read

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

The IRC 199A qualified business income deduction is the single largest deduction available to pass-through business owners, and it is the provision that most directly narrows the tax rate gap between pass-through entities (taxed at individual rates up to 37%) and C-corporations (taxed at a flat 21%). Under IRC 199A, an individual taxpayer who owns a pass-through business can deduct up to 20% of their qualified business income, which effectively reduces the top marginal rate on pass-through income from 37% to 29.6%. The deduction was enacted as part of the Tax Cuts and Jobs Act in 2017 and was originally scheduled to expire after December 31, 2025. The One Big Beautiful Bill Act (OBBBA) made the deduction permanent and updated the income thresholds. The deduction applies to domestic business income from a trade or business conducted through a sole proprietorship, partnership, S-Corp, trust, or estate. It doesn’t apply to C-Corp income, W-2 wages, capital gains, interest, or dividends. Understanding the limitations (W-2 wage/UBIA test, SSTB phase-out, and the overall taxable income cap) is essential for maximizing the deduction.

✓Key takeaway

IRC 199A QBI deduction overview:

Element	Details
Maximum deduction	20% of qualified business income
Who can take it	Individuals, trusts, and estates with pass-through business income
Entity types	Sole proprietorship, partnership, LLC, S-Corp (not C-Corp)
Where it’s taken	Individual return (Form 1040, line 13)
Reduces AGI?	No (below-the-line deduction from taxable income)
Reduces SE tax?	No (calculated on net earnings before QBI deduction)
Made permanent	Yes (OBBBA, signed 2025)

Income thresholds (2025, OBBBA-adjusted):

Filing Status	Full Deduction Below	Phase-Out Range	No SSTB Deduction Above
Single	$191,950	$191,951-$266,950	$266,950
MFJ	$383,900	$383,901-$533,900	$533,900

Limitation summary by income level:

Income Level	Non-SSTB Business	SSTB Business
Below threshold	20% QBI (no limitations)	20% QBI (no limitations)
In phase-out range	Phase in W-2/UBIA limitation	Phase out deduction entirely
Above threshold	W-2/UBIA limitation applies fully	$0 deduction

How does the QBI deduction work?

Hypothetical example

Round numbers. Three business owners, each with $400,000 in qualified business income, filing MFJ.

Scenario 1: Non-SSTB, below threshold (simple) Owner of a manufacturing business. Taxable income: $350,000 (below $383,900).

Item	Amount
QBI	$400,000
QBI deduction (20%)	$80,000
Limitations?	None (below threshold)
Tax savings (37% on $80,000)	$29,600

Scenario 2: Non-SSTB, above threshold (W-2/UBIA limitation) Owner of a manufacturing S-Corp. Taxable income: $600,000 (above $533,900).

Item	Amount
QBI	$400,000
Tentative QBI deduction (20%)	$80,000
W-2 wages paid by business	$200,000
UBIA of qualified property	$500,000

W-2/UBIA limitation (greater of):

Test	Calculation	Result
50% of W-2 wages	$200,000 x 50%	$100,000
25% of W-2 wages + 2.5% of UBIA	($200,000 x 25%) + ($500,000 x 2.5%)	$62,500
Greater of the two		$100,000

Item	Amount
QBI deduction (lesser of 20% QBI or W-2/UBIA limit)	$80,000 (20% of $400K is less than $100K limit)
Deduction	$80,000
Tax savings (37%)	$29,600

If the business paid only $100,000 in W-2 wages and had $0 UBIA:

Test	Result
50% of $100,000 W-2 wages	$50,000
25% of $100,000 + 2.5% of $0	$25,000
Greater of the two	$50,000
QBI deduction (lesser of $80K or $50K)	$50,000 (limited)
Lost deduction	$30,000
Lost tax savings	$11,100

Scenario 3: SSTB, above threshold Attorney (law firm). Taxable income: $600,000 (above $533,900).

Item	Amount
QBI	$400,000
Tentative QBI deduction (20%)	$80,000
SSTB limitation	Fully phased out at $533,900 MFJ
QBI deduction	$0
Lost tax savings	$29,600

The SSTB list (IRC 199A(d)(2)):

SSTB Category	Examples
Health care	Physicians, dentists, veterinarians, pharmacists, nurses, psychologists
Law	Attorneys, paralegals (if law firm)
Accounting	CPAs, enrolled agents, bookkeepers (if accounting firm)
Actuarial science	Actuaries
Performing arts	Actors, musicians, entertainers
Consulting	Management consultants, strategy consultants
Athletics	Professional athletes, coaches, team owners
Financial services	Financial advisors, wealth managers, investment bankers
Brokerage services	Stock brokers, insurance brokers, real estate brokers
Any business where principal asset is reputation or skill	Varies (narrow; generally celebrities monetizing their name)

Non-SSTB businesses that get the full deduction:

Business Type	QBI Eligible?
Manufacturing	Yes (full 20%)
Construction	Yes
Real estate (rental, development)	Yes
Retail	Yes
Wholesale/distribution	Yes
Restaurant/food service	Yes
Technology (product companies)	Yes
Agriculture/farming	Yes
Trucking/transportation	Yes
E-commerce	Yes

Strategies to maximize the QBI deduction:

For W-2/UBIA-limited businesses:

Strategy	Effect
Increase W-2 wages (hire employees vs. contractors)	Raises the 50% W-2 ceiling
Purchase qualified property (equipment, vehicles)	Raises the UBIA component
Pay owner a higher W-2 salary (S-Corp)	Owner salary counts as W-2 wages for the test
Accelerate equipment purchases before year-end	Increases UBIA for that year

For SSTB-classified businesses:

Strategy	Effect
Keep taxable income below threshold	Full deduction available
Maximize retirement contributions	Reduces taxable income below SSTB threshold
Maximize charitable contributions	Same effect
Separate non-SSTB activities into a different entity	Non-SSTB income gets QBI deduction
PTET election	Does not affect QBI (entity-level tax is not a QBI deduction substitute)

QBI deduction vs. C-Corp rate comparison:

Income Level	S-Corp Effective Rate (with QBI)	C-Corp Rate (with double tax)	Winner
$100,000	19.2% (24% bracket, 20% QBI deduction)	21% + 15% on distributions = ~32%	S-Corp
$300,000	26.4% (33% effective, 20% QBI)	21% + 23.8% = ~39%	S-Corp
$500,000 (non-SSTB)	29.6% (37% bracket, 20% QBI)	21% + 23.8% = ~39%	S-Corp
$500,000 (SSTB, no QBI)	37%	21% + 23.8% = ~39%	Close (S-Corp avoids double tax)
$1,000,000 (reinvesting all profits)	29.6-37%	21% (no distributions)	C-Corp (if not distributing)

Common QBI deduction mistakes:

Mistake	Consequence
Claiming QBI on W-2 wages	W-2 income is not QBI
Claiming QBI on rental income without trade or business status	Rental must be a trade or business (safe harbor: 250+ hours)
Not aggregating businesses	Aggregation can help meet the W-2/UBIA test (Reg. 1.199A-4)
Not tracking UBIA	Missing the 2.5% UBIA component when wages alone are insufficient
S-Corp salary too low	Lower salary = lower W-2 wages = lower QBI ceiling (but also lower SE tax; balance needed)
Not separating non-SSTB activities	Lost QBI deduction on income that could qualify

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

Related guides:

QBI Deduction for Rental Real Estate: The Safe Harbor Under Rev. Proc. 2019-38

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. "IRC 199A Qualified Business Income Deduction: Complete Guide to the 20% Pass-Through Deduction." Blue Cloud CPA, September 5, 2026. https://bluecloudcpa.com/guides/small-business-irc-199a-qualified-business-income-deduction-comprehensive

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