If you work for yourself, a Solo 401(k) is one of the most powerful retirement accounts available to you. It lets you contribute as both the employee and the employer, which means you can sock away far more than you could with a SEP IRA or a standard IRA. Here’s everything you need to know.
What Is a Solo 401(k)?
A Solo 401(k) — also called an Individual 401(k), a One-Participant 401(k), or a Self-Employed 401(k) — is a retirement plan designed for self-employed individuals who have no full-time employees other than themselves and their spouse. It follows the same rules as a standard workplace 401(k) but is set up for sole proprietors, freelancers, independent contractors, and single-member LLCs.
Who Qualifies for a Solo 401(k)?
You qualify if you:
- Are self-employed with net business income
- Have no full-time W-2 employees (your spouse is an exception)
- Operate as a sole proprietor, LLC, partnership, or S-corp
If you have employees who work 1,000 or more hours per year, you’d need to offer them coverage too — which often means switching to a traditional 401(k) plan.
Solo 401(k) Contribution Limits for 2026
This is where the Solo 401(k) really shines. You can contribute in two capacities:
- As the employee: Up to $23,500 in elective deferrals (or $31,000 if you’re 50 or older, thanks to catch-up contributions)
- As the employer: Up to 25% of your net self-employment income
The total combined limit is $70,000 in 2026 ($77,500 with catch-up). That’s a significant advantage over a SEP IRA, which only allows employer contributions of up to 25% of compensation.
For example, if your net self-employment income is $100,000, you could contribute $23,500 as the employee plus $25,000 as the employer — a total of $48,500 in a single year.
Roth vs. Traditional Solo 401(k)
Many Solo 401(k) providers offer both traditional and Roth options:
- Traditional: Contributions are pre-tax, reducing your taxable income now. You pay taxes on withdrawals in retirement.
- Roth: Contributions are after-tax. Qualified withdrawals in retirement are completely tax-free.
If you expect to be in a higher tax bracket in retirement, or you’re younger with decades of compounding ahead, the Roth Solo 401(k) can be a powerful choice. If you need the tax break today, traditional is the better call.
Solo 401(k) vs. SEP IRA
| Feature | Solo 401(k) | SEP IRA |
|---|---|---|
| 2026 Contribution Limit | Up to $70,000 | Up to $70,000 |
| Roth Option | Yes | No (SEP Roth exists but is uncommon) |
| Loan Provision | Yes (up to $50,000) | No |
| Employee Deferrals | Yes | No |
| Setup Complexity | Moderate | Simple |
| Best For | High earners who want max contributions | High earners who want simplicity |
At lower income levels, the Solo 401(k) typically allows larger contributions because you can add employee deferrals on top of employer contributions. A SEP IRA only allows employer-side contributions.
How to Open a Solo 401(k)
- Choose a provider. Fidelity, Vanguard, Charles Schwab, and E*TRADE all offer free Solo 401(k) plans with low-cost index funds. Fidelity and Schwab currently have no annual fees.
- Get an EIN. Even as a sole proprietor, you’ll need an Employer Identification Number from the IRS (free, takes minutes at IRS.gov).
- Complete the plan documents. Your brokerage will walk you through the adoption agreement.
- Start contributing. You can make employee deferrals any time during the tax year. Employer contributions must be made by the tax filing deadline (plus extensions).
Important deadline: The plan itself must be established by December 31 of the tax year for which you want to make contributions. Don’t wait until April.
Can You Take a Loan From a Solo 401(k)?
Yes — unlike an IRA, a Solo 401(k) can allow loans of up to 50% of your vested balance or $50,000, whichever is less. Not all providers support this feature, so check before you open an account if the loan option matters to you.
What Are the Tax Advantages?
- Traditional contributions reduce your current taxable income, which directly lowers your self-employment tax as well
- Roth contributions grow tax-free and are withdrawn tax-free in retirement
- Employer contributions are deductible as a business expense
Is a Solo 401(k) Right for You?
A Solo 401(k) is one of the best retirement accounts available if:
- You’re self-employed with no full-time employees
- You want to maximize contributions, especially at moderate income levels
- You want a Roth option
- You might need a loan from the plan one day
If you have employees, a SEP IRA or SIMPLE IRA may be simpler. But for solo operators who want to build serious retirement wealth, the Solo 401(k) is hard to beat.
Bottom Line
A Solo 401(k) lets self-employed workers contribute as both the employee and employer, with a combined limit of up to $70,000 in 2026. It offers more flexibility than a SEP IRA, includes a Roth option, and allows loans. Open one before December 31 of the year you want to start contributing.