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If you built your business alone and opened a Solo 401(k) along the way, you made a smart move. A Solo 401(k), also called an Individual 401(k), gives self-employed business owners one of the most powerful retirement savings structures available. High contribution limits, flexibility, and the ability to hold alternative assets like real estate, promissory notes, private placements, precious metals, and cryptocurrency make it a compelling option for the solo operator.
But what happens the day you hire your first employee?
That question catches more small business owners off guard than almost any other retirement planning scenario. The answer matters, and understanding it now, before it becomes urgent, gives you the options and control you need to make informed decisions.
A Solo 401(k) is a qualified retirement plan specifically designed for self-employed individuals and business owners with no full-time W-2 employees other than themselves and their spouse. This distinction is critical. The plan was designed for one-person operations, and the IRS eligibility rules reflect that precisely.
To maintain a Solo 401(k), your business generally cannot have any full-time employees other than you (and your spouse, if applicable). For this purpose, a full-time employee is typically defined as someone who works 1,000 hours or more per year. Part-time workers who log fewer than 1,000 hours annually may not trigger disqualification, but that threshold requires careful tracking and documentation.
The moment you hire a full-time employee who meets the plan's eligibility requirements, the Solo 401(k) structure is no longer available to you in its current form. This isn't a gray area. It's a defined eligibility rule.
The Solo 401(k) is one of the most generous retirement savings vehicles for self-employed individuals. For 2026, the contribution limits are structured as follows:
These limits represent a significant opportunity to build retirement savings, far beyond what a Traditional or Roth IRA alone allows. Losing access to this structure through an unplanned hiring decision is a real and avoidable risk.
When your business takes on a qualifying employee, a few specific things happen to your Solo 401(k):
First, your plan must be amended or replaced. A Solo 401(k) can only cover eligible business owners. Once a non-owner employee meets the eligibility requirements under your plan documents, you are generally required to either expand the plan to cover them or terminate the Solo 401(k) and transition to a different plan structure.
Second, if the plan is expanded, it becomes a standard 401(k) plan, and with that comes additional responsibilities. You may be subject to nondiscrimination testing, Form 5500 filing requirements (once assets exceed $250,000), and the obligation to offer comparable benefits to eligible employees.
Third, ignoring the change is not an option. Continuing to operate a Solo 401(k) after hiring a qualifying employee without addressing plan eligibility can result in plan disqualification, which carries serious tax consequences.
The good news: you have options. Understanding each one gives you the control to make the right decision for your business.
Option 1: Amend the Solo 401(k) into a Standard 401(k)
The Solo 401(k) can be converted into a traditional 401(k) plan. This expands coverage to include eligible employees. You take on employer responsibilities, including potential matching or non-elective contributions, but you retain the plan structure you know and continue building retirement savings. The self-directed component can often be preserved with a Record Keeping Account with your SDIRA plan Administrator. Just make sure that your new 401(k) plan documents allow it.
Option 2: Transition to a SEP IRA
A Simplified Employee Pension (SEP) IRA is another popular option for small business owners with employees. For 2026, employer contributions can reach up to 25% of compensation with a maximum of $72,000. SEP IRAs are employer-funded only, employees do not make salary deferrals, which simplifies administration. SEP IRAs can also be self-directed, giving you direct access to alternative assets.
Option 3: Establish a SIMPLE IRA
A SIMPLE IRA is designed specifically for small businesses with 100 or fewer employees. For 2026, employees can defer up to $17,000 (under 50) or $21,000 / $22,250 (50 and over / ages 60-63). Employers are required to make either a 3% matching contribution or a 2% non-elective contribution. SIMPLE IRAs must generally be established by October 1 of the plan year.
Option 4: Terminate the Solo 401(k)
In some cases, especially if the business is transitioning significantly, terminating the Solo 401(k) and rolling the assets into an IRA or a new plan structure may be the cleanest path forward. Assets rolled into a Self-Directed IRA can maintain access to alternative assets like real estate, promissory notes, private placements, precious metals, and cryptocurrency.
It's worth understanding one nuance: not every hire automatically disqualifies your Solo 401(k). Employees who work fewer than 1,000 hours per year are generally excluded from eligibility. If your business relies on seasonal or truly part-time workers who stay below that threshold, your Solo 401(k) may remain intact, but documentation is essential.
Additionally, there are some plan document variations that define eligibility differently. Review your specific plan documents and consult with a qualified plan administrator or legal counsel to understand your exact thresholds.
One of the most common concerns for business owners who hold alternative assets inside their Solo 401(k) is what happens to those holdings during a transition. Real estate, promissory notes, private placements, and precious metals don't liquidate on a timetable that always aligns with administrative deadlines.
If you're transitioning to a standard 401(k) that allows self-directed options, your existing holdings may transfer in kind, depending on the new plan's structure and custodian. If you're rolling assets to a Self-Directed IRA, in-kind transfers may also be possible, though specific rules apply.
This is another reason why planning ahead, before the hire, not after, is so valuable. You preserve the flexibility to structure the transition in a way that protects your existing positions.
Business growth and hiring often happens fast. The administrative and legal timelines for retirement plan changes don't always move at the same speed. Here's what to keep in mind:
Getting ahead of these deadlines gives you the most flexibility.
If you currently have a Solo 401(k) and are considering hiring, here are the key steps to take:
Mountain West IRA specializes in self-directed retirement account administration. While we do not provide financial, legal, or tax advice, we can help you understand the administrative side of self-directed retirement accounts and what options may be available to you.
Mountain West IRA can help you open a Self-Directed IRA or Solo 401(k), so you can invest in what you know best.
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This post is for informational purposes only and should not be considered financial advice. Please consult with a financial advisor for personalized advice.
Mountain West IRA, Inc. does not render tax, legal, accounting, investment, or other professional advice. If accounting, tax, legal, investment, or other similar expert assistance is required, the services of a competent professional should be sought.
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