If you are self-employed, choosing the right retirement plan can significantly affect how much you save and how much you pay in taxes over time.
Many independent professionals in their 30s and 40s, including consultants, real estate agents, physicians, and creators, eventually face the same question:
Should I open a Solo 401(k) or a SEP IRA?
Both plans allow business owners to save aggressively for retirement while reducing taxable income. However, the rules around contributions, taxes, and employee eligibility are different.
At District Capital Management, we often help business owners evaluate which retirement plan fits best within a broader strategy that includes holistic financial planning and long-term tax planning.
This guide explains how Solo 401(k)s and SEP IRAs work, their key differences, and when each option may make sense.
Key Takeaways
- Both Solo 401(k)s and SEP IRAs allow self-employed individuals to make large retirement contributions.
- A Solo 401(k) allows contributions as both employer and employee.
- A SEP IRA allows contributions only as the employer.
- Solo 401(k)s may allow higher contributions at lower income levels.
- SEP IRAs are often simpler to administer, especially for businesses with employees.
What Is a Solo 401(k)?
A Solo 401(k), also called an individual 401(k), is a retirement plan designed for self-employed individuals with no full-time employees other than a spouse.
This plan functions similarly to a traditional employer 401(k), but it is tailored for small business owners.
A key advantage is that the owner can contribute in two ways:
- Employee contribution
- Employer contribution
Because of this structure, Solo 401(k)s often allow higher savings for individuals with moderate business income.
You can learn more about how this plan works in our detailed guide to Solo 401(k) retirement plans.
What Is a SEP IRA?
A SEP IRA (Simplified Employee Pension IRA) is a retirement plan designed for small businesses and self-employed individuals.
Unlike a Solo 401(k), contributions are made only by the employer.
If you have employees, the employer must contribute the same percentage of salary for each eligible employee.
For example, if the business contributes 10 percent of the owner’s compensation, it must also contribute 10 percent for all eligible employees.
SEP IRAs are often chosen because they are simple to establish and maintain compared with other retirement plans.
Solo 401(k) vs SEP IRA: Quick Comparison
| Feature | Solo 401(k) | SEP IRA |
|---|---|---|
| Who qualifies | Self-employed with no employees | Self-employed or small businesses |
| Contribution types | Employee + employer | Employer only |
| Maximum contribution (2025) | Up to $70,000 depending on income | Up to $70,000 depending on income |
| Roth option | Often available | Not available |
| Employee eligibility | Cannot have non-spouse employees | Must include eligible employees |
| Administration | Slightly more complex | Very simple |
Contribution Limits: Solo 401(k) vs SEP IRA
For the 2026 tax year, the total contribution limit for both plans is generally:
Up to $72,000
However, how those contributions are calculated differs.
SEP IRA Contributions
SEP contributions are limited to:
Up to 25 percent of compensation
In practice, the effective limit often works out closer to 20 percent of net self-employment income after adjustments.
Solo 401(k) Contributions
A Solo 401(k) allows two contributions:
Employee contribution
- $24,500 in 2026
- $32,500 if age 50+
- $35,750 if age 60–63
Employer contribution
Up to 25 percent of compensation
Because of the employee portion, Solo 401(k)s often allow higher contributions at lower income levels.
For professionals trying to maximize tax-advantaged savings, this flexibility can make a meaningful difference.
Contribution Deadlines
Both plans generally follow the same contribution deadline.
Contributions can typically be made until the tax filing deadline, including extensions.
For example:
2025 contributions may be made until April 15, 2026.
This flexibility can be useful for business owners who want to make retirement contributions after calculating their final income for the year.
Tax Treatment: Solo 401(k) vs SEP IRA
Both plans provide valuable tax benefits.
SEP IRA Tax Treatment
SEP IRA contributions are tax-deductible, meaning they reduce current taxable income.
However, withdrawals during retirement are taxed as ordinary income.
Solo 401(k) Tax Treatment
Solo 401(k)s may offer more flexibility.
Depending on the provider, contributions can be:
- Traditional (pre-tax)
- Roth (after-tax)
Roth contributions allow investments to grow tax-free, which can be attractive for individuals who expect higher tax rates in retirement.
Understanding which approach fits your situation often requires broader tax planning alongside retirement strategies like Roth conversions.
Administrative Complexity
Both plans are relatively straightforward, but there are some differences.
SEP IRA Setup
SEP IRAs are extremely simple.
Typically, you only need to:
- Open an account with a provider
- Complete Form 5305-SEP
There are no annual IRS filings required.
Solo 401(k) Setup
Solo 401(k)s are also simple to open but have slightly more administrative requirements.
Once plan assets exceed $250,000, the plan owner must file Form 5500-EZ annually.
For many self-employed professionals, this extra step is minor compared with the additional savings potential.
Which Plan Is Better?
There is no universal answer.
Solo 401(k) may be better if:
- You have no employees
- You want to maximize contributions
- You want access to Roth contributions
- You want more flexibility in tax planning
SEP IRA may be better if:
- You have employees
- You want minimal administrative work
- You prefer a simple retirement structure
For many independent professionals, a Solo 401(k) often provides greater flexibility and higher potential savings.
However, each business structure is different.
Frequently Asked Questions
Yes, but the combined contribution limits still apply. Having both accounts does not allow you to double your contributions.
If your business hires eligible W-2 employees, the plan can no longer remain a Solo 401(k). It may need to be converted into a standard 401(k) plan that includes employees.
Many Solo 401(k) providers allow Roth contributions. SEP IRAs do not offer Roth contributions.
Some Solo 401(k) plans allow participant loans, depending on the provider. SEP IRAs do not allow loans.
Yes. Once plan assets exceed $250,000, the plan owner must file Form 5500-EZ annually with the IRS.
Both Solo 401(k)s and SEP IRAs may accept rollovers from certain retirement accounts. However, rules vary by provider and should be confirmed before initiating a rollover.
A Solo 401(k) typically allows higher contributions at lower income levels because it includes both employee and employer contributions.
SEP IRAs automatically adjust contributions based on profits. Solo 401(k)s allow employee contributions even during lower income years, which can provide more flexibility.
Final Thoughts
Both Solo 401(k)s and SEP IRAs can be powerful tools for self-employed professionals who want to save for retirement and reduce taxes.
For many individuals with no employees, a Solo 401(k) offers greater flexibility and higher contribution potential.
However, the best choice depends on your business structure, income stability, and long-term goals.
Work With a Fee-Only Financial Planner
Choosing the right retirement plan is only one part of building long-term financial security.
At District Capital Management, we help professionals integrate retirement planning, taxes, and investments into a comprehensive strategy.
If you want help evaluating whether a Solo 401(k) or SEP IRA fits your situation, consider speaking with a fee-only financial advisor.
You can schedule a complimentary discovery call with our team to discuss your financial plan.
Alvin Carlos, CFP®, CFA is a fee-only financial planner, in Washington, D.C. He has a Master’s degree in International Relations from SAIS-Johns Hopkins. Alvin is the founder of District Capital, a financial planning firm designed to help professionals in their 30s and 40s maximize their money and retire by 55, through holistic financial planning and research-driven investing. Schedule a free discovery call today.
