When it comes to self-directed retirement accounts like the Solo 401(k), few topics are more important — or more confusing — than understanding who is a “disqualified person.” The IRS has strict rules in place, and one wrong move could turn a tax-advantaged investment into a prohibited transaction, leading to penalties and taxable distributions.
Watch: Find out Who is a Disqualified Person for solo 401k Investing Purposes
This blog post breaks down the key rules, explains who qualifies as a disqualified person, and highlights practical examples to help you avoid costly mistakes.
Why This Matters
Your Solo 401(k) allows for powerful investing opportunities beyond Wall Street — including real estate, private equity, promissory notes, and more. However, these freedoms come with boundaries. If you transact with a disqualified person, you risk triggering a prohibited transaction that could invalidate your tax shelter.
The good news? With proper understanding and planning, you can keep your investments compliant and your retirement funds safe.
Who Is a Disqualified Person?
According to IRS rules, disqualified persons include:
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You, the account owner
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Your spouse
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Your parents and grandparents (biological or adoptive)
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Your children and grandchildren (including their spouses)
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Entities owned or controlled by you or other disqualified persons
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Service providers to the plan (for example, a CPA preparing your Solo 401(k) filings)
These restrictions exist to prevent “self-dealing” — situations where you or close family members benefit personally from Solo 401(k) assets.
Common Prohibited Transactions
Here are some real-world examples that often come up:
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Renting property to family: You cannot buy a rental with your Solo 401(k) and then let your parents or children live there, even at market rent.
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Funding your business: You cannot loan Solo 401(k) money to your own company or your spouse’s company.
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Selling your own property: You cannot sell a house or asset you own to your Solo 401(k), even at fair market value.
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Loaning funds to disqualified persons: Loans to your children, spouse, or parents are prohibited.
Who Is Not a Disqualified Person?
Interestingly, not all relatives fall under the disqualified person rule. The following relationships are not disqualified:
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Siblings (brothers and sisters)
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Cousins
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Friends or unrelated business contacts
However, when dealing with these groups, you must still ensure all transactions are at fair market value. For example, if you loan Solo 401(k) funds to your brother via a promissory note, you should charge an interest rate comparable to what a bank would charge based on creditworthiness
Best Practices to Stay Compliant
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Always Ask First – Before making an investment, run the idea by your Solo 401(k) provider, CPA, or tax attorney.
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Document Properly – Promissory notes, appraisals, and loan agreements should always be formal and IRS-compliant.
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Avoid “Too Clever” Structures – If an investment feels complicated or like a workaround, it probably crosses the IRS’s line.
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Use Fair Market Value – Ensure all transactions with non-disqualified persons are done at true market value.
Key Takeaway
The Solo 401(k) is one of the most flexible and powerful retirement accounts available to self-employed individuals. But with that power comes responsibility. By understanding who counts as a disqualified person and avoiding prohibited transactions, you can protect your tax-advantaged status and build wealth with confidence.
When in doubt, remember this rule of thumb: If it benefits you or your close family personally outside of retirement savings, it’s probably prohibited.
✅ Need help navigating Solo 401(k) rules? Reach out to your plan provider or tax advisor before making your next investment decision. A quick check today can save you thousands in penalties tomorrow.
