One of the most common—and most misunderstood—questions self-employed individuals ask is:
“What is the profit-sharing percentage for a Solo 401(k)?”
The answer depends on how your business is taxed, and understanding this distinction can unlock tens of thousands of dollars in additional, tax-advantaged retirement savings each year.
Let’s break it down clearly.
Watch: Solo 401k Profit Sharing Employer aka Nonelective Contributions Broken Down
What Is a Solo 401(k) Profit-Sharing Contribution?
A profit-sharing contribution is an employer contribution made by your self-employed business to your Solo 401(k) plan.
You may also see it referred to as:
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Employer contribution
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Employer profit-sharing contribution
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Non-elective contribution (IRS terminology)
All of these terms mean the same thing:
A contribution made by the business, not withheld from employee wages.
Like employee deferrals, profit-sharing contributions are:
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Discretionary
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Not required every year
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Based solely on earned self-employment income
Who Is Eligible for a Solo 401(k)?
Before discussing percentages, it’s important to confirm eligibility.
You qualify for a Solo 401(k) if:
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You are self-employed
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You do not employ full-time, non-owner W-2 employees working 1,000+ hours per year
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Contractors in your business do not count as employees
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Employees under age 21 may be excluded
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Your business structure may be:
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Sole proprietorship
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Single-member LLC
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Partnership
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S-Corporation
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C-Corporation
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The key factor is earned income from active work, not passive income such as rentals, dividends, or capital gains.
Profit-Sharing Percentage by Business Type
Sole Proprietorship or Single-Member LLC (Taxed as Sole Prop)
If your business income is reported on Schedule C, the maximum profit-sharing contribution is:
Up to 20% of net self-employment income
Why 20% and not 25%?
Because sole proprietors must first subtract ½ of self-employment tax, which creates a circular calculation that effectively caps the contribution at 20%.
Example:
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Net Schedule C income (after SE tax adjustment): $100,000
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Maximum profit-sharing contribution: $20,000
S-Corporation
If your business is taxed as an S-Corp, the calculation is more favorable.
Up to 25% of W-2 wages paid to yourself
Only W-2 compensation counts—distributions do not qualify.
Example:
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W-2 wages: $100,000
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Maximum profit-sharing contribution: $25,000
This advantage is one of the main reasons high-income self-employed individuals elect S-Corp taxation.
Does a Day-Job 401(k) Affect Solo 401(k) Profit Sharing?
No.
This is a powerful—and often overlooked—planning opportunity.
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Employer profit-sharing contributions are not aggregated across unrelated employers
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A day-job 401(k) does not reduce what you can contribute to your Solo 401(k)
This means you can:
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Receive employer contributions at your W-2 job and
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Make full employer profit-sharing contributions to your Solo 401(k) based on self-employment income
The aggregation rules apply to employee deferrals, not employer profit-sharing contributions or to voluntary after-tax solo 401k contributions.
Can Solo 401(k) Profit-Sharing Be Roth?
Yes—thanks to SECURE Act 2.0, Solo 401(k) plans may now allow Roth employer profit-sharing contributions.
However, this strategy requires careful analysis.
How Roth Profit-Sharing Works
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The business still deducts the contribution
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The amount is treated as a taxable in-plan Roth conversion on your personal return
When Does Roth Profit-Sharing Make Sense?
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Most often for S-Corporation owners
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Because profit-sharing contributions are not subject to self-employment tax
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Allows for long-term tax-free growth while avoiding SE tax
For sole proprietors, Roth profit-sharing is usually inefficient due to exposure to both income and self-employment taxes.
Key Takeaways
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Solo 401(k) profit-sharing = employer / non-elective contributions
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Sole proprietors & partnerships: up to 20% of net self-employment income
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S-Corporations: up to 25% of W-2 wages
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Day-job employer contributions do not limit Solo 401(k) profit-sharing
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Roth profit-sharing is permitted but typically best suited for S-Corp owners
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Voluntary after-tax contributions (Mega Backdoor Roth) are often a more efficient Roth strategy
Final Thoughts
Understanding how Solo 401(k) profit-sharing works—and how it differs by entity type—can dramatically increase your retirement savings while reducing taxes.
When structured correctly, a Solo 401(k) is one of the most powerful retirement tools available to self-employed professionals.
