SEP IRA Vs. Solo 401(K): Which Retirement Plan Is Better For Self-Employed Business Owners?

If you're self-employed or own a small business with no full-time employees, choosing the right retirement plan can help you save thousands of dollars in taxes while building long-term wealth. Two of the most popular options are the SEP IRA and the Solo 401(k).

Both plans offer tax advantages and allow substantial retirement contributions, but they work differently. Depending on your income, business structure, and retirement goals, one may provide significantly more flexibility and higher contribution opportunities than the other.

In this guide, we'll compare SEP IRAs and Solo 401(k) plans to help determine which retirement plan may be the better fit for your situation.

What Is a SEP IRA?

A Simplified Employee Pension (SEP) IRA is a retirement plan designed for self-employed individuals and small business owners. Contributions are made solely by the employer and are generally tax-deductible.

SEP IRAs are known for their simplicity, low administrative burden, and relatively high contribution limits.

Key SEP IRA Benefits

• Easy to establish and maintain

• No annual filing requirements

• Tax-deductible employer contributions

• High contribution limits

• Available through most custodians and brokerage firms

SEP IRA Contribution Limits

For 2026, contributions can generally be made up to 25% of compensation, subject to annual IRS limits.

For sole proprietors, the calculation is slightly more complex because contributions are based on adjusted net self-employment income.

What Is a Solo 401(k)?

A Solo 401(k), also known as an Individual 401(k), is designed for self-employed individuals and business owners who have no full-time employees other than a spouse.

Unlike a SEP IRA, a Solo 401(k) allows you to contribute as both the employee and the employer, often resulting in larger retirement contributions at lower income levels.

Key Solo 401(k) Benefits

• Higher contribution potential for many business owners

• Employee salary deferral contributions

• Employer profit-sharing contributions

• Roth contribution options in many plans

• Loan provisions may be available

• Ability to make catch-up contributions if eligible

SEP IRA vs. Solo 401(k): Key Differences

Contribution Flexibility

The biggest difference between these plans is how contributions are made.

With a SEP IRA, all contributions are employer contributions.

With a Solo 401(k), you can contribute as:

1. Employee (salary deferral)

2. Employer (profit-sharing contribution)

This dual contribution structure often allows business owners to save significantly more at lower income levels.

Example: $100,000 of Self-Employment Income

A business owner earning approximately $100,000 may be able to contribute:

SEP IRA

• Roughly 20% of adjusted net earnings

• Approximately $20,000 contribution

Solo 401(k)

• Employee contribution

• Employer contribution

• Potentially much higher total contribution

For many self-employed professionals, consultants, and small business owners, the Solo 401(k) provides the ability to maximize retirement savings much faster.

Roth Contributions

SEP IRAs do not offer traditional Roth contribution flexibility.

Many Solo 401(k) plans allow Roth employee contributions, providing tax-free growth potential for retirement.

This feature can be especially attractive for younger business owners or those expecting higher future tax rates.

Borrowing Options

SEP IRAs do not permit participant loans.

Many Solo 401(k) plans allow loans, subject to IRS rules and plan provisions.

While borrowing from retirement accounts should generally be approached cautiously, some business owners value having access to this flexibility.

Administrative Requirements

SEP IRAs are generally simpler.

A Solo 401(k) may require additional paperwork and annual filings once plan assets exceed IRS thresholds.

For many business owners, the additional flexibility outweighs the modest administrative requirements.

When a SEP IRA May Make Sense

A SEP IRA may be a good fit if:

• You want the simplest retirement plan available

• You have fluctuating income

• You prefer minimal paperwork

• You plan to contribute only employer contributions

• You need a retirement plan established quickly

Many freelancers, independent contractors, and sole proprietors appreciate the ease of administration that comes with a SEP IRA.

When a Solo 401(k) May Make Sense

A Solo 401(k) may be a better fit if:

• You want to maximize retirement contributions

• Your income is under the level where SEP and Solo 401(k) contributions become similar

• You want Roth contribution options

• You may benefit from participant loan provisions

• Your spouse works in the business and can also participate

For many self-employed professionals, the Solo 401(k) is often the most powerful retirement savings vehicle available.

What If I Have Employees?

This is an important consideration.

A Solo 401(k) is generally intended for business owners with no full-time employees other than a spouse.

If you hire eligible employees, additional retirement plan rules may apply.

Similarly, SEP IRA plans require employer contributions for eligible employees, which can become expensive as a business grows.

Business owners with employees may want to evaluate other retirement plans such as:

• Safe Harbor 401(k)

• Traditional 401(k)

• SIMPLE IRA

• Cash Balance Pension Plans

SEP IRA vs. Solo 401(k): Which Is Better?

For many self-employed business owners with no employees, the Solo 401(k) often provides greater flexibility and larger contribution opportunities.

However, the "best" plan depends on your income level, business structure, tax situation, and retirement goals.

A SEP IRA may be ideal for someone seeking simplicity, while a Solo 401(k) may be the better choice for someone looking to maximize retirement savings and tax benefits.

Frequently Asked Questions

Can I have both a SEP IRA and a Solo 401(k)?

In some circumstances, yes. However, contribution rules can become complex and may limit the advantages of maintaining both plans.

Is a Solo 401(k) always better than a SEP IRA?

Not necessarily. A Solo 401(k) often allows higher contributions at lower income levels, but a SEP IRA may be easier to administer.

Which retirement plan allows larger contributions?

For many self-employed individuals, a Solo 401(k) allows larger contributions because it includes both employee and employer contribution components.

Can my spouse participate in my Solo 401(k)?

Yes. If your spouse earns compensation from the business, they may be able to participate and make contributions, potentially increasing your household's retirement savings.

Final Thoughts

Choosing between a SEP IRA and a Solo 401(k) is one of the most important retirement planning decisions a self-employed individual can make. The right choice can help reduce taxes, accelerate retirement savings, and create greater financial flexibility.

Because contribution limits, tax deductions, and eligibility requirements can vary based on your income and business structure, it's often helpful to work with a financial advisor and tax professional before selecting a plan.

At Coastal Wealth Management, we help self-employed professionals and business owners evaluate retirement plan options, maximize tax-efficient savings strategies, and build comprehensive retirement plans designed around their long-term goals.