You own two LLCs. One has a payroll of half a million dollars and not much equipment. The other owns the building and a fleet of trucks, but pays nobody — it just leases assets to operating affiliates. Your taxable income last year crossed the Section 199A phase-in threshold. When your accountant runs the QBI deduction separately on each entity, the wage-light entity throws off almost no deduction because its W-2 wages and UBIA of qualified property are near zero. The other entity has plenty of wages but not enough QBI to soak them up.
That mismatch is the precise problem the Section 199A aggregation election was designed to fix. Treasury Reg 1.199A-4 lets you treat the two businesses as a single economic unit for the wage-and-property limitation, which often unlocks deduction dollars that the silo-by-silo calculation forfeits. The catch: aggregation is a one-way ratchet, it has five strict eligibility tests, and a missed disclosure on Form 8995-A Schedule B can blow up the election entirely. This guide walks through how aggregation works, who actually benefits, and the procedural traps that catch first-time filers.
Why Aggregation Exists
Section 199A gives owners of pass-through businesses — sole proprietorships, partnerships, S corporations, and certain trusts — a deduction of up to 20% of qualified business income. Below the 2026 phase-in thresholds ($201,750 single, $403,500 joint), you get the full deduction with no wage test. Above the phase-out cap ($276,750 single, $553,500 joint after the wider OBBBA range), the deduction is fully limited by the greater of:
- 50% of W-2 wages paid by the qualified trade or business, or
- 25% of W-2 wages plus 2.5% of the unadjusted basis immediately after acquisition (UBIA) of qualified property.
When you operate through multiple entities, the statute applies that limitation trade or business by trade or business. If one entity has all the wages and another has all the QBI, the math punishes the separation. Aggregation lets you pool the W-2 wages, UBIA, and QBI across qualifying related businesses before the limitation is calculated. For owners of operating-leasing structures, multi-store franchisees, or holding-and-management-company setups, the difference can be tens or hundreds of thousands of deduction dollars.
The Five Tests You Must Pass
Reg 1.199A-4 spells out five eligibility requirements. You need to satisfy all of them to aggregate.
1. Control Test (50% Common Ownership)
The same person or group of persons must own 50% or more of each trade or business being aggregated, directly or by attribution under IRC Sections 267(b) (family attribution) or 707(b) (partnership attribution). For an S corporation, that means 50% or more of the issued and outstanding shares. For a partnership, it means 50% or more of the capital or profits interest.
A "group of persons" can include spouses, children, parents, siblings, and certain trusts under the family attribution rules. So three siblings who each own one-third of two LLCs satisfy the control test as a group, even though no individual hits 50% alone.
2. Majority Test
The common ownership has to exist for a majority of the taxable year and must be in place on the last day of the year. If you bought into a new venture mid-year and got to 50% on June 1, you do not qualify for aggregation that year. Plan acquisitions and restructures around this rule — closing on December 30 doesn't help if the majority was only there for two days.
3. Same-Year Test
All aggregated businesses must use the same taxable year, not counting short tax years. A calendar-year S corp can't aggregate with a fiscal-year partnership. If you want the option later, harmonize the year-ends now.
4. Non-SSTB Test
None of the aggregated trades or businesses can be a specified service trade or business (SSTB). SSTBs include health, law, accounting, actuarial science, performing arts, consulting, athletics, financial services, brokerage services, investing and investment management, trading, dealing in securities or partnership interests, and any business whose principal asset is the reputation or skill of one or more employees. If even one entity in the proposed aggregation is an SSTB, the whole group is disqualified.
5. Connection Test (At Least Two of Three Factors)
The businesses must be operationally connected. You need to check at least two of these three boxes:
- Same or complementary products/services — They provide products, property, or services that are the same or are customarily offered together (e.g., a hardware store and a tool rental shop).
- Shared facilities or centralized functions — They share facilities or significant centralized business elements such as personnel, accounting, legal, manufacturing, purchasing, HR, or IT.
- Operational coordination — They are operated in coordination with, or reliance upon, one or more of the businesses in the group (think supply-chain interdependence or one entity that exists primarily to support the others).
This is the test that lets a real-estate-holding LLC aggregate with the operating company that leases the building, as long as they share back-office functions or were set up to work together.
What Aggregation Actually Does to the Math
When you aggregate, you combine the QBI, W-2 wages, and UBIA of qualified property across all aggregated trades or businesses before applying the wage-and-property limitation. The pre-cap deduction is still 20% of QBI, but the cap is now computed on the combined pool.
A Simple Worked Example
Suppose you own two S corporations that share back-office staff and are operated as a single business.
- OpCo: $800,000 QBI, $600,000 W-2 wages, $0 UBIA
- PropCo: $200,000 QBI, $0 W-2 wages, $4,000,000 UBIA
You are over the upper threshold. Without aggregation:
- OpCo deduction cap = greater of 50% × $600,000 = $300,000 or 25% × $600,000 + 2.5% × $0 = $150,000 → cap = $300,000. Tentative 20% × $800,000 = $160,000. Deduction = $160,000.
- PropCo deduction cap = greater of 50% × $0 = $0 or 25% × $0 + 2.5% × $4,000,000 = $100,000 → cap = $100,000. Tentative 20% × $200,000 = $40,000. Deduction = $40,000.
- Total = $200,000.
With aggregation:
- Combined QBI = $1,000,000; combined wages = $600,000; combined UBIA = $4,000,000.
- Cap = greater of 50% × $600,000 = $300,000 or 25% × $600,000 + 2.5% × $4,000,000 = $250,000 → cap = $300,000.
- Tentative 20% × $1,000,000 = $200,000.
- Total deduction = $200,000.
In this example, the silo-by-silo math actually keeps pace because each entity hits its own cap comfortably. Aggregation tends to shine when one entity has plenty of wages or property and another has lots of QBI but neither resource. Flip PropCo to have $400,000 QBI and OpCo to have $400,000 wages with $200,000 QBI: separately, PropCo's $80,000 tentative deduction is capped at $5,000 (2.5% of $200,000 UBIA, assuming smaller property), while aggregated the deduction climbs to the full 20% of combined QBI.
The lesson: aggregation is a planning math problem, not a default. Run both calculations.
Aggregation Can Happen at Two Levels
The final regulations let aggregation happen at either the relevant pass-through entity (RPE) level or the individual owner level. An RPE — a partnership or S corporation — can aggregate its own trades or businesses and report the aggregation to its owners on the Schedule K-1. An owner who receives an already-aggregated K-1 must respect that aggregation but is not bound by it across the rest of their personal return — they can layer their own additional aggregations of other K-1 businesses or sole proprietorships, as long as the combined group still satisfies the five tests.
What an owner cannot do is undo an aggregation chosen at the RPE level or substitute a different grouping for the businesses the RPE already aggregated.
Reporting on Form 8995-A Schedule B
Aggregation only counts if you tell the IRS. Schedule B of Form 8995-A (the long-form QBI worksheet for taxpayers above the threshold) is the disclosure form. Every year you claim an aggregation, you must attach Schedule B and provide:
- A description of each trade or business in the aggregated group.
- The name and EIN of each entity.
- A statement of the facts that satisfy the ownership, majority, same-year, non-SSTB, and connection tests.
- Any change in facts and circumstances since the prior year.
Missed the disclosure? The aggregation is disregarded for that year. You can't fix it by claiming the aggregation existed all along — the regulations specifically authorize the IRS to disaggregate undisclosed groupings.
The Consistency Rule
Once you elect to aggregate, you are locked in. You must report the same aggregation in every subsequent year. The election is irrevocable unless there is a material change in the facts and circumstances that disqualifies the grouping — for example, you sell down to below 50% ownership, an SSTB enters the group, or the centralized functions that gave you the connection test go away.
If a new business is added that meets the five tests, you may include it in the existing aggregation in the year it qualifies. You cannot, however, selectively drop a business from the group just because it would help your math in a given year.
Who Should Aggregate
Aggregation is most valuable for taxpayers above the phase-in threshold whose entities have mismatched resources. Common patterns:
- Operating company + real estate LLC. The classic split. The real estate entity owns the building with lots of UBIA; the operating company has wages and QBI. Aggregation lets the operating company's QBI benefit from the real estate entity's basis cushion.
- Multi-location franchisees. Several entities each owning a store, with shared back-office staff in one management company. Wages may be lopsided across stores; aggregation smooths the limitation.
- Holding company with multiple operating subsidiaries. As long as none are SSTBs and they share enough centralized functions, grouping them often unlocks more deduction.
- Family-owned business groups. Use the attribution rules to satisfy the 50% control test even if no single family member owns a majority of every entity.
It is rarely useful when:
- Your taxable income is below the phase-in threshold (no wage test applies, so aggregation has no math effect).
- You only own one trade or business.
- One of your entities is an SSTB (disqualifying).
- All your entities already have plenty of wages and UBIA relative to their QBI.
Common Pitfalls
- Real estate as a "trade or business." Aggregation requires each component to qualify as a Section 162 trade or business. A single net-leased property with no active management likely isn't one. Look to the Section 199A real estate safe harbor (Rev. Proc. 2019-38) or build the activity facts before relying on aggregation.
- Failing the same-year test. Mixed calendar/fiscal year groups are surprisingly common in family businesses. You need to convert before you can aggregate.
- Forgetting the connection test factors. "We're owned by the same people" is the control test, not the connection test. You need at least two of the three operational factors.
- Letting an SSTB sneak in. A consulting subsidiary or in-house brokerage arm can disqualify the whole aggregation. Carve it out as a separate non-aggregated business.
- Reporting differently each year. Once aggregated, you must report consistently. Don't let a new preparer "reset" the grouping.
- Treating the election as automatic. The IRS may disaggregate any group that isn't disclosed on Schedule B. The disclosure is not optional and not waivable.
When to Run the Numbers — and When to Restructure
Aggregation is a tax-return-time election, but the eligibility tests reach back into how you structured the businesses in the first place. If you are planning a recapitalization, a real estate spin-out, or a new acquisition, ask the aggregation question early. Bringing in a 49% outside investor on one entity in the group will tank the control test for the whole group. Moving a service line into a separate entity to "clean up" the structure can accidentally create an SSTB that poisons the aggregation.
A practical workflow:
- Inventory the entities. Ownership percentages, year-ends, primary activities, whether they pay W-2 wages, and UBIA of qualified property.
- Map the five tests. Identify which groupings pass and which fail, and why.
- Run the deduction both ways. Compute QBI deduction with and without aggregation; if the gap is small, the administrative burden may not be worth it.
- Pick the optimal grouping. Multiple valid aggregations may exist — for example, you might aggregate A+B+C, or just A+B and leave C separate.
- Document the connection facts. Memorialize the shared services, supply-chain ties, or coordinated operations now so you have contemporaneous support if audited.
- File Schedule B every year and update the disclosure if facts change.
Keep Your Pass-Through Records Audit-Ready
Whether or not aggregation makes sense for your QBI deduction, the prerequisite to running the analysis is having clean, structured books across all of your pass-through entities. Intercompany allocations, payroll splits across related entities, and per-entity UBIA tracking are exactly the data points the IRS will want to see if your Schedule B disclosure draws scrutiny.
Beancount.io is a plain-text accounting platform that gives you complete transparency and version control over every entity in your business group — no black boxes, no vendor lock-in, and a structure that lets your CPA or tax software pull the wage, QBI, and basis figures directly without reconciliation drama. Get started for free and see why owners of multi-entity pass-through structures are switching to plain-text accounting.