Solo 401k vs SEP IRA
Max Contribution Calculator
Find out exactly which retirement account allows you to shelter more of your income from taxes.
Which is Better: Solo 401k or SEP IRA?
For self-employed individuals, both accounts offer massive tax deductions, but they calculate maximum contributions differently:
- SEP IRA: You can only contribute as the “Employer” (up to 20% of your net adjusted self-employment income).
- Solo 401k: You can contribute as BOTH the “Employee” (a flat limit) AND the “Employer” (up to 20% of net income).
Because the Solo 401k allows double-dipping, it almost always allows you to shelter significantly more money at lower income brackets.
⚙️ Advanced IRS Limits (Fully Editable)
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Self-Employed Retirement Guide
Solo 401k vs SEP IRA: Which Is Better in 2026?
If you are a freelancer, independent contractor, or sole proprietor with no full-time W-2 employees, choosing the right retirement account is the single most important tax decision you will make. Using a Solo 401k vs SEP IRA calculator is the fastest way to determine which retirement plan gives you the highest tax savings based on your specific business profit.
Both accounts offer incredible tax shelters, but the way they calculate maximum limits differs entirely. Using a reliable self-employed retirement calculator to compare the two options will reveal a massive difference in potential tax savings, especially at income levels below $250,000.
| Feature | Solo 401k | SEP IRA |
|---|---|---|
| Contribution Type | Employee + Employer | Employer Only |
| Max Contribution Potential | Much Higher (Double-dipping) | Lower (Tied directly to profit) |
| Catch-Up Limits (Age 50+) | Yes ($7,500 to $11,250) | No Catch-up Available |
| Best For | Freelancers, Single-Member LLCs | Simple setup, High Income Earners |
Solo 401k Contribution Limits (2025/2026 Explained)
A Solo 401k (also known as an Individual 401k) allows you to act as both the employee and the employer of your own business. This unique structure means you can contribute to the account twice. Here is how the limits break down for 2025, according to official IRS guidelines:
- Employee Contribution: You can contribute up to 100% of your earned income up to $23,500.
- Catch-up Contributions: If you are aged 50 to 59 (or 64+), you can add an extra $7,500. Thanks to the SECURE 2.0 Act, if you are aged 60 to 63, you get a “super catch-up” of $11,250.
- Employer Profit-Sharing: On top of your employee deferral, your business can contribute up to 20% of your net adjusted business profit.
The absolute maximum combined contribution (base) across both categories for 2025 is $70,000. You can use our solo 401k contribution calculator above to dynamically adjust your exact cap based on your Schedule C profit.
SEP IRA Contribution Rules Explained
Unlike a Solo 401k, a Simplified Employee Pension (SEP) IRA does not allow you to make standard “employee” salary deferrals. You are restricted to making employer contributions only.
Under IRS rules, you can contribute up to 25% of your compensation. However, if you are a sole proprietor or single-member LLC, you must calculate this based on your adjusted net earnings, which mathematically reduces your actual maximum contribution limit to roughly 20% of your net business profit.
The hard cap for SEP IRA contributions in 2025 is also $70,000, but because you lack the flat $23,500 employee deferral, you need a significantly higher business income to reach that maximum cap. A good sep ira calculator will instantly show you how heavily this 20% limit caps your tax shelter potential.
Real Example: $100,000 Income Comparison
To truly understand why these two accounts output drastically different numbers, let’s look at the math for a freelancer who earns exactly $100,000 in net self-employment income (profit after business expenses).
After deducting half of your estimated self-employment taxes (~$7,065), your Adjusted Net Earnings sit at about $92,935.
| Account Type | The Math | Total Allowed Contribution |
|---|---|---|
| SEP IRA | 20% of $92,935 | ~$18,587 |
| Solo 401k | $23,500 (Employee) + $18,587 (Employer 20%) | ~$42,087 |
The Result: At $100,000 of income, the Solo 401k allows you to shelter over $23,000 more from taxes than the SEP IRA. For mid-tier earners, the Solo 401k is mathematically superior.
When a SEP IRA Is Actually Better
If the Solo 401k allows for higher contributions, why do thousands of business owners still open SEP IRAs? A SEP IRA may be a better choice if you prioritize simplicity and want a retirement plan with zero administrative friction.
- Easier Setup: Opening a SEP IRA takes five minutes online and requires no complex plan documents.
- No Annual Paperwork: Once a Solo 401k reaches $250,000 in assets, you must file a Form 5500-EZ with the IRS every year. SEP IRAs never require this form.
- Very High Income Earners: If your net profit exceeds $350,000, you will likely hit the $70,000 IRS maximum using the 20% employer contribution alone. In this case, the Solo 401k loses its advantage, and the simplicity of the SEP IRA wins out.
How to Choose Between Solo 401k and SEP IRA
Making your final decision boils down to your income level and your appetite for paperwork. Use this checklist to guide your decision:
👉 Choose a Solo 401k if:
- You want absolute maximum tax savings.
- Your net income is under ~$250,000 (where the employee contribution makes a massive difference).
- You are 50 or older and want to make catch-up contributions.
- You want the option to take a loan from your retirement account (Solo 401ks allow loans; SEP IRAs do not).
👉 Choose a SEP IRA if:
- You want absolute simplicity with zero IRS reporting requirements.
- Your business income is high enough that 20% of your profit easily maxes out your retirement goals.
- You plan to hire full-time W-2 employees in the near future (a Solo 401k must be closed or transitioned if you hire non-spouse employees).