Quick Answer
Controlled group rules treat related companies (80%+ common ownership) as a single employer for 401(k) purposes. This means shared contribution limits, combined nondiscrimination testing, and unified eligibility requirements. About 15% of businesses are affected, typically family-owned companies or those with complex ownership structures.
Best Answer
Sarah Chen, CPA
Best for business owners, executives with equity stakes, or employees of related companies
What are controlled group rules for 401(k) plans?
Controlled group rules require that businesses with common ownership be treated as a single employer for retirement plan purposes. If two or more companies are in a controlled group, they must aggregate their 401(k) plans for contribution limits, nondiscrimination testing, and eligibility requirements.
The IRS uses these rules to prevent business owners from artificially splitting their business to avoid 401(k) limitations or create unfair advantages for highly compensated employees.
Types of controlled groups
Parent-subsidiary controlled group: One corporation owns 80% or more of another corporation.
Brother-sister controlled group: The same 5 or fewer individuals own 80% or more of each corporation AND more than 50% in identical ownership.
Combined group: A mixture of parent-subsidiary and brother-sister relationships.
Example: Brother-sister controlled group affecting 401(k)
John owns 60% of ABC Corp (his consulting business) and 70% of XYZ Corp (his real estate company). His wife Maria owns 25% of ABC Corp and 20% of XYZ Corp.
Ownership analysis:
Result: This IS a controlled group because:
1. Same people (John + Maria) own 80%+ of each company ✓
2. Identical ownership exceeds 50% (60%) ✓
How controlled group status affects your 401(k)
1. Shared contribution limits
If you work for multiple controlled group companies, your annual additions limit ($70,000 in 2026) applies across ALL the companies combined, not separately.
Example impact:
2. Combined nondiscrimination testing
All controlled group companies must pass nondiscrimination tests together. This means:
3. Unified eligibility and vesting
Service with any controlled group company counts toward:
Controlled group testing thresholds
What you should know if you're affected
Business owners: You cannot avoid 401(k) limits by creating multiple companies. Work with a qualified plan administrator who understands controlled group rules.
Executives with equity: Your stock options or ownership stake might create controlled group relationships you're not aware of. This affects your contribution limits if you work for multiple related companies.
Family business employees: Family attribution rules mean your relatives' ownership counts as yours for controlled group purposes.
Common misconceptions
"We have separate EINs, so we're separate employers." Wrong. Tax ID numbers don't determine controlled group status — ownership percentages do.
"We operate in different industries." Irrelevant. A construction company and a restaurant can still be a controlled group if they have common ownership.
"The companies have separate 401(k) plans." The plans can remain separate, but they must be administered as if they're one employer for testing and limits.
What you should do
1. Map your ownership relationships if you own or work for multiple companies
2. Consult a qualified plan administrator annually to ensure proper controlled group testing
3. Coordinate 401(k) contributions across all controlled group employers
4. Review attribution rules for family members' ownership stakes
5. Consider plan design changes if controlled group status creates compliance issues
Use our paycheck calculator to model how controlled group limits might affect your retirement contributions across multiple employers.
Key takeaway: Companies with 80%+ common ownership must treat their 401(k) plans as a single employer, sharing the $70,000 annual additions limit and requiring combined nondiscrimination testing.
Key Takeaway: Companies with 80%+ common ownership must treat their 401(k) plans as a single employer, sharing contribution limits and requiring combined compliance testing.
Controlled group ownership thresholds and tests
| Test Type | Threshold | Example | Result |
|---|---|---|---|
| Parent-subsidiary | 80% ownership | Corp A owns 85% of Corp B | Controlled group |
| Brother-sister | 80% common + 50% identical | Same family owns 80%+ of both companies | Controlled group |
| Attribution rules | Family = one person | Husband owns 40%, wife owns 45% | 85% combined = controlled group |
| Separate owners | No common control | Unrelated parties own each company | Not controlled group |
More Perspectives
Marcus Rivera, CFP
Best for employees who work for multiple companies that might be related
How to know if your employers are a controlled group
As an employee working for multiple companies, you might not realize they're related under controlled group rules. Here's how to identify if your employers are connected:
Look for common ownership signs:
Ask HR or payroll directly: "Are we part of a controlled group with any other companies for 401(k) purposes?"
Example: Restaurant employee with two jobs
Sarah works 25 hours/week at "Mike's Pizza" earning $25,000 annually and 20 hours/week at "Mike's Catering" earning $20,000 annually. She assumes these are separate employers.
However, Mike owns 85% of both companies, making them a controlled group. This means:
Impact on your contributions
If your multiple employers are a controlled group:
Action step: If you suspect your employers are related, ask each HR department about controlled group status before maximizing 401(k) contributions.
Key takeaway: Employees working for multiple related companies share a single $70,000 annual additions limit, not separate limits for each employer.
Key Takeaway: Employees working for multiple related companies share a single $70,000 annual additions limit and must coordinate contributions across all employers.
Sarah Chen, CPA
Best for pre-retirees who own businesses or have complex employment situations
Controlled groups and retirement transition planning
If you're approaching retirement and own or work for related companies, controlled group rules can significantly impact your final years of retirement savings.
Example: Business owner planning retirement
Dr. Johnson, age 62, owns a medical practice (85% ownership) and a medical real estate company (90% ownership). As a controlled group, his retirement contributions are limited across both entities:
Without controlled group awareness:
With controlled group rules:
Strategic considerations for pre-retirees
Plan coordination becomes critical in your final working years when contribution limits are highest and the tax benefits most valuable.
Consider business structure changes if controlled group status significantly limits your retirement savings. However, any restructuring must be done for legitimate business purposes, not solely to avoid controlled group rules.
Time your retirement carefully if you're transitioning from employee to consultant. The year you change roles, service with the controlled group companies might affect your eligibility for different types of contributions.
Review annually because ownership percentages can change, potentially moving companies in or out of controlled group status.
Key takeaway: Pre-retirees with business ownership must coordinate retirement contributions across all controlled group companies to avoid exceeding the age-based annual additions limits.
Key Takeaway: Business owners approaching retirement must carefully coordinate contributions across controlled group companies to maximize age-based catch-up limits without excess contributions.
Sources
- IRC Section 414(b) and (c) — Definitions and special rules for controlled group of corporations
- IRS Revenue Ruling 2008-42 — Controlled group determination examples
Reviewed by Sarah Chen, CPA on February 28, 2026
This content is for educational purposes only and is not a substitute for professional tax advice. Consult a qualified tax professional for advice specific to your situation.