Solo 401(k) vs SEP-IRA: Which Saves More for Self-Employed People in 2026?
Both Solo 401(k) and SEP-IRA let self-employed people save significantly for retirement while reducing their tax bill. But they reach their contribution limits very differently — and for most freelancers earning under $175,000, the Solo 401(k) allows substantially higher contributions. This guide shows you the exact numbers at different income levels so you can make the right choice.
2026 Contribution Limits at a Glance
| Solo 401(k) | SEP-IRA | |
|---|---|---|
| Employee deferral | Up to $24,500 | None |
| Employer contribution | Up to 25% of W-2 wages (S-Corp) or ~20% of net income (sole prop) | Up to 25% of compensation (~20% net for sole prop) |
| Combined total cap | $72,000 ($80,000 with catch-up age 50+) | $72,000 |
| IRA catch-up (age 50+) | $8,000 additional | Not applicable |
| Deadline to establish | December 31 of the tax year | Tax filing deadline including extensions |
| Deadline to contribute | Tax filing deadline (employee deferral must be designated by Dec 31) | Tax filing deadline including extensions |
Source: IRS Notice 2025-67, IRS Publication 560 (2026)
Why the Solo 401(k) Almost Always Wins at Lower Incomes
The key difference is the employee deferral feature of the Solo 401(k). As the employee of your own business, you can contribute up to $24,500 regardless of what percentage of your income that represents. This feature doesn't exist in a SEP-IRA.
SEP-IRA contributions are limited to 25% of compensation — which for a sole proprietor works out to approximately 20% of net self-employment income after the SE tax deduction. At lower incomes, this percentage cap makes SEP-IRA contributions much smaller than what a Solo 401(k) allows.
Side-by-Side Comparison at Different Income Levels
| Net SE Income | Solo 401(k) Max Contribution | SEP-IRA Max Contribution | Solo 401(k) Advantage |
|---|---|---|---|
| $40,000 | ~$31,500 (deferral + employer) | ~$7,400 | +$24,100 |
| $60,000 | ~$36,000 | ~$11,100 | +$24,900 |
| $80,000 | ~$40,500 | ~$14,800 | +$25,700 |
| $100,000 | ~$43,000 | ~$18,600 | +$24,400 |
| $150,000 | ~$54,500 | ~$27,900 | +$26,600 |
| $200,000 | ~$64,500 | ~$37,200 | +$27,300 |
| $275,000+ | $72,000 (cap reached) | $72,000 (cap reached) | Equal |
The gap between Solo 401(k) and SEP-IRA closes at approximately $275,000 in net self-employment income, where both accounts hit their $72,000 combined cap. Below that income level, the Solo 401(k) is almost always the better choice.
Tax Savings Comparison
At $80,000 net income in the 22% federal tax bracket:
- Solo 401(k): Contribute ~$40,500 → reduce taxable income by $40,500 → save ~$8,910 in income tax + reduce SE tax base
- SEP-IRA: Contribute ~$14,800 → reduce taxable income by $14,800 → save ~$3,256 in income tax
- Difference: ~$5,654 more in tax savings with Solo 401(k)
When SEP-IRA Makes More Sense
Despite the Solo 401(k)'s contribution advantage, the SEP-IRA wins in specific situations:
You have employees (other than a spouse)
Solo 401(k) is strictly for businesses with no full-time employees other than the owner and their spouse. The moment you hire a full-time employee, you can no longer use a Solo 401(k). SEP-IRA can be used regardless of employee count — though you must contribute the same percentage for eligible employees as you do for yourself.
You want simplicity
SEP-IRA requires almost no administration — open an account at any brokerage, contribute by your tax filing deadline, done. No annual reports, no plan documents. Solo 401(k) requires establishing a plan document, and plans with over $250,000 in assets must file Form 5500-EZ annually.
You want maximum flexibility on timing
SEP-IRA contributions can be made up to your tax filing deadline including extensions — potentially as late as October 15 of the following year. With a Solo 401(k), the employee elective deferral must be designated by December 31 (though the cash can be contributed later). If you don't realize you want to maximize retirement savings until March, a SEP-IRA gives you more time.
Your income is above $275,000
At high income levels, both accounts hit the $72,000 combined cap anyway. SEP-IRA's simplicity advantage outweighs the Solo 401(k)'s features when the contribution limits are the same.
Can You Have Both?
Yes — you can maintain both a Solo 401(k) and a SEP-IRA, but the combined contributions across both are still subject to the $72,000 total annual limit. Having both doesn't allow you to double-contribute; it just gives you flexibility in how you allocate between the two account types.
One practical reason to have both: if you have a part-time job or other retirement plan through a separate employer, your employee deferral limit applies across all plans. Keeping a SEP-IRA as a secondary vehicle for employer-equivalent contributions in years when you've already maxed employee deferrals elsewhere can be useful.
Solo 401(k) Setup: What You Need to Know
The Solo 401(k) must be established by December 31 of the tax year you want it to apply to. You cannot open one in March and retroactively apply it to the prior tax year (unlike a SEP-IRA).
Where to open one: Fidelity, Vanguard, Charles Schwab, and E*TRADE all offer free Solo 401(k) plans. For self-directed options (investing in real estate, private equity), specialized providers like IRA Financial or Rocket Dollar offer more investment flexibility at higher cost.
How Retirement Contributions Interact With Quarterly Taxes
Retirement contributions reduce your net self-employment income, which directly lowers your quarterly estimated tax payments. If you contribute $30,000 to a Solo 401(k), your SE tax base drops by $30,000 — reducing your quarterly payments accordingly.
Use our Quarterly Tax Estimator to see how your retirement contribution strategy affects your quarterly payment obligations. You can also check whether S-Corp election could amplify your retirement savings — S-Corp owners can contribute based on their W-2 salary, which changes the employer contribution calculation.
Frequently Asked Questions
Can I open a Solo 401(k) if I have a full-time W-2 job as well?
Yes — you can open a Solo 401(k) for your self-employment income even if you also have a W-2 job. However, the employee elective deferral limit ($24,500) applies across all your 401(k) plans combined. If you've already contributed $24,500 to your employer's 401(k), you can only make employer (profit-sharing) contributions to your Solo 401(k). The employer side is separate and isn't limited by contributions to other plans.
What's the deadline to open a Solo 401(k) for the current tax year?
December 31 of the current tax year. This is a hard deadline — you cannot open a Solo 401(k) retroactively. Once the plan is established by December 31, you have until your tax filing deadline (including extensions) to actually deposit the contribution. So you can open the plan in December and contribute the cash in April or October.
Do Solo 401(k) contributions reduce self-employment tax?
Yes, indirectly. SE tax is calculated on your net self-employment income. Solo 401(k) contributions (the employer profit-sharing portion specifically) reduce your net income and therefore reduce the SE tax base. The employee elective deferral portion does not reduce SE tax — it reduces income tax. This is a nuance that many freelancers miss when calculating their quarterly payments.
What happens to my Solo 401(k) if I hire an employee?
Once you hire a full-time employee (working 1,000+ hours per year who isn't your spouse), you must either convert your Solo 401(k) to a regular 401(k) plan (which requires offering benefits to eligible employees) or terminate the Solo 401(k) and open an alternative plan. This is a significant administrative change — something to plan for if you're considering hiring your first employee.