SEP IRA vs Solo 401k: Which Retirement Plan Is Better for You?

If you’re self-employed or run a small business with no or few employees, choosing the right retirement plan is a critical decision. Two of the most popular options are the SEP IRA and the Solo 401k. Both offer tax advantages and the potential for high contribution limits, but they differ in important ways that can impact your long-term savings.

As retirement planners, we often help clients weigh these two plans based on their income, business structure, and retirement goals. Let’s walk through the pros and cons of each, and highlight which one might be a better fit for your situation.

SEP IRA: Simplified Employee Pension Plan

A SEP IRA is a retirement plan that allows employer contributions for self-employed individuals and small business owners.

Pros:

Easy to Set Up and Maintain: SEP IRAs are simple to establish with minimal paperwork and no annual filing requirements with the IRS.
High Contribution Limits: You can contribute up to 25% of your net earnings from self-employment, up to a maximum of $70,000 in 2025.
Flexible Contributions: You’re not locked into a fixed contribution each year. You can vary the amount or skip a year altogether.
Works for Small Businesses: If you have employees, you can contribute for them too, making this an attractive option for small teams.

Cons:

Employer-Only Contributions: Only the employer can contribute. Employees (including yourself as the owner) can’t make elective deferrals.
Equal Percentage Rule: If you contribute for yourself, you must contribute the same percentage of compensation for each eligible employee.
No Roth Option: SEP IRAs are traditional only, so there’s no Roth version to allow for after-tax contributions.

Solo 401k: Also Known as an Individual 401k

A Solo 401k is designed for self-employed individuals and business owners with no employees (other than a spouse).

Pros:

Higher Contribution Potential: You can contribute both as the employee (up to $23,500 in 2025, or $31,000 if age 50+) and as the employer (up to 25% of compensation), allowing for total contributions of up to $70,000 or $77,500 with catch-up.
Roth Option Available: Many Solo 401k providers offer a Roth component, allowing you to contribute after-tax dollars for tax-free growth.
Loan Option: Some Solo 401ks allow you to borrow from your account up to $50,000 or 50% of the balance.

Cons:

More Paperwork: Solo 401ks require more setup, and once your plan balance exceeds $250,000, you must file Form 5500 annually.
Strict Eligibility: If you hire any full-time employees (besides your spouse), you will no longer qualify for a Solo 401k.
Less Flexibility for Employer Contributions: Employer contributions are based on a fixed formula and require some careful calculation.

SEP IRA vs Solo 401k: Which One Should You Choose?

Here are some things to consider when choosing between a SEP IRA and a Solo 401k:

Choose a SEP IRA if:

You value simplicity and minimal paperwork.
You want a flexible plan that allows you to skip contributions in lower-income years.
You have employees and want to make contributions for them.
You don’t need a Roth option or plan to take loans from your retirement plan.

Choose a Solo 401k if:

You want to maximize your retirement contributions, especially if your income is lower, but you still want to save aggressively.
You want access to Roth contributions or the ability to take a loan.
You have no employees (other than a spouse).
You’re willing to handle a little more paperwork for greater flexibility and control.

SEP IRA vs Solo 401k: Bottom Line

Both the SEP IRA and Solo 401k are great retirement planning tools for self-employed individuals and small business owners. The “better” option comes down to your specific situation, including your income, business structure, desire for Roth contributions, and willingness to manage plan requirements.

If you’re unsure which plan fits best, contact Zynergy Retirement Planning today. We can help you assess your options and ensure your retirement strategy aligns with your goals.