IRC 199A QBI Aggregation and Planning: How to Maximize the 20% Pass-Through Deduction

By Yarik Yarosh, CPA ·September 5, 2026 ·6 min read

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

The 20% QBI deduction is the largest annual tax benefit available to most pass-through business owners, but it is also one of the most complex provisions in the tax code. The deduction is straightforward below the income thresholds ($266,950 single / $533,900 MFJ under the OBBBA-updated amounts): 20% of qualified business income, limited to the lesser of 20% of QBI or 20% of taxable income (before the QBI deduction). Above the thresholds, the deduction is limited by the W-2 wages/UBIA test, and it phases out entirely for specified service trades or businesses (SSTBs). The aggregation election under Reg. 1.199A-4 is the primary planning tool for taxpayers above the income threshold: by combining businesses that share common ownership, the W-2 wages from all aggregated businesses are pooled, often unlocking a larger deduction than any single business could produce on its own. The election is binding once made (it continues until the aggregation criteria are no longer met or the taxpayer revokes it, which generally cannot be done retroactively), so the decision requires analysis of the W-2 wages, UBIA, and income of each business, modeled under both aggregated and non-aggregated scenarios.

✓Key takeaway

QBI deduction calculation (above-threshold taxpayers):

Step	Calculation
1. Calculate QBI for each business	Net qualified business income (excluding capital gains, interest income, reasonable compensation)
2. Calculate the W-2 wages/UBIA limitation	Greater of: (a) 50% of W-2 wages, OR (b) 25% of W-2 wages + 2.5% of UBIA
3. QBI deduction for each business	Lesser of: 20% of QBI or the W-2/UBIA limitation
4. Combined QBI deduction	Sum of all businesses, limited to 20% of taxable income (before QBI deduction)

Aggregation requirements (Reg. 1.199A-4):

Requirement	Details
Common ownership	Same person or group of persons owns 50%+ of each business (directly or indirectly)
Reporting consistency	All aggregated businesses must be reported on the same return
At least 2 of 3 factors	(1) Products/services are of the same type, (2) shared facilities or centralized business functions, (3) coordinated or integrated operations
Cannot aggregate SSTBs with non-SSTBs	SSTBs can only be aggregated with other SSTBs
Binding election	Once made, generally must be maintained in future years

How does aggregation maximize your QBI deduction?

Hypothetical example

Round numbers. A taxpayer (MFJ, $700,000 total taxable income before QBI) owns two businesses:

Business A: Real estate management company (S-Corp)

Item	Amount
QBI	$300,000
W-2 wages paid	$400,000
UBIA of qualified property	$50,000

Business B: Real estate holding LLC (rental properties)

Item	Amount
QBI (rental income after expenses)	$200,000
W-2 wages paid	$0 (no employees)
UBIA of qualified property	$3,000,000

Without aggregation (each business calculated separately):

Business A:

Test	Amount
20% of QBI	$60,000
50% of W-2 wages	$200,000
25% of W-2 + 2.5% of UBIA: ($100,000 + $1,250)	$101,250
Greater of the two W-2/UBIA tests	$200,000
QBI deduction: lesser of $60,000 or $200,000	$60,000

Business B:

Test	Amount
20% of QBI	$40,000
50% of W-2 wages	$0
25% of W-2 + 2.5% of UBIA: ($0 + $75,000)	$75,000
Greater of the two W-2/UBIA tests	$75,000
QBI deduction: lesser of $40,000 or $75,000	$40,000

Total QBI deduction without aggregation: $100,000 Tax savings (37%): $37,000

With aggregation (both businesses combined):

Item	Combined
QBI	$500,000
20% of QBI	$100,000
W-2 wages (combined)	$400,000
UBIA (combined)	$3,050,000
50% of W-2 wages	$200,000
25% of W-2 + 2.5% of UBIA: ($100,000 + $76,250)	$176,250
Greater of the two W-2/UBIA tests	$200,000
QBI deduction: lesser of $100,000 or $200,000	$100,000

Total QBI deduction with aggregation: $100,000 Same result in this scenario because Business A’s W-2 wages already exceed the limitation.

Scenario where aggregation matters more:

Business A (consulting firm, NON-SSTB):

Item	Amount
QBI	$400,000
W-2 wages	$100,000
UBIA	$20,000

Business B (staffing company, NON-SSTB):

Item	Amount
QBI	$100,000
W-2 wages	$500,000
UBIA	$10,000

Without aggregation:

Business A:

Test	Amount
20% of QBI	$80,000
50% of W-2	$50,000
25% of W-2 + 2.5% of UBIA	$25,500
QBI deduction: lesser of $80,000 or $50,000	$50,000

Business B:

Test	Amount
20% of QBI	$20,000
50% of W-2	$250,000
QBI deduction: lesser of $20,000 or $250,000	$20,000

Total without aggregation: $70,000

With aggregation:

Item	Combined
QBI	$500,000
20% of QBI	$100,000
W-2 wages	$600,000
50% of W-2	$300,000
QBI deduction: lesser of $100,000 or $300,000	$100,000

Total with aggregation: $100,000 Aggregation savings: $30,000 ($11,100 in tax at 37%)

Business A’s income is constrained by its low W-2 wages, while Business B has excess W-2 wages. Aggregation allows Business B’s excess W-2 wages to support Business A’s QBI deduction.

W-2 wage computation methods (Rev. Proc. 2019-11):

Method	How It Works
Unmodified Box 1 method	W-2 wages = total Box 1 amounts on all W-2s filed by the business
Modified Box 1 method	Start with Box 1; subtract amounts not included in Box 1 (certain fringe benefits), add amounts included in Box 1 that should not be counted
Revenue Procedure cost allocation method	Allocate total W-2 wages to QBI activities based on the wages attributable to the qualified business

Planning strategies to maximize QBI:

Strategy	How It Works
Aggregate businesses with excess W-2 wages and businesses with excess QBI	Pool the W-2 wages to unlock the full 20% deduction
Purchase qualified property (UBIA)	Increases the 25% + 2.5% alternative test; particularly useful for businesses with low W-2 wages
Increase W-2 wages (hire employees instead of contractors)	More W-2 wages = higher limitation
Manage taxable income (stay below SSTB threshold)	Retirement plan contributions, charitable giving, and timing of income can keep taxable income below $266,950/$533,900
Separate SSTB and non-SSTB activities	If part of a business is SSTB and part is not, proper separation may preserve the QBI deduction on the non-SSTB portion
Elect S-Corp (reasonable salary vs. distribution split)	W-2 wages paid to the owner count toward the limitation, but reduce QBI by the same amount

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

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Cite this page

Yarik Yarosh, CPA. "IRC 199A QBI Aggregation and Planning: How to Maximize the 20% Pass-Through Deduction." Blue Cloud CPA, September 5, 2026. https://bluecloudcpa.com/guides/small-business-irc-199a-qualified-business-income-aggregation-strategies

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