SEP IRA vs Solo 401k comes down to one thing for most self-employed people: a Solo 401(k) usually lets you save more on the same net income, while a SEP IRA is simpler to run. Both are tax-advantaged retirement accounts for the self-employed, both let you put away up to $72,000 in 2026, and both beat leaving your profit in a checking account. The difference is how you get to that number.
A Solo 401(k) adds a flat, tax-deductible employee contribution on top of the employer piece, so you maximize your total at a lower income. A SEP IRA is pure simplicity, with one employer contribution and almost no paperwork. Want the most savings and a Roth option? The Solo 401(k) usually wins. Want the easiest possible setup? The SEP IRA is hard to beat. New to retirement accounts in general? Start with our guide to how to open an IRA or Roth IRA, then come back here. For more on building income you can invest, the whole Personal Profitability library is built for hustlers and entrepreneurs.
SEP IRA vs Solo 401k: the short answer
For most one-person businesses, a Solo 401(k) lets you contribute more at the same income, and a SEP IRA is easier to open and run. Both cap out at the same $72,000 total for 2026, and both are funded with pre-tax dollars that grow tax-deferred. The split is about how each one calculates your contribution and how much paperwork it costs you. Here is the side-by-side.
| Feature | SEP IRA | Solo 401(k) |
|---|---|---|
| Who it is for | Self-employed, can have eligible employees | Self-employed with no employees (spouse OK) |
| 2026 max contribution | $72,000 | $72,000 (plus catch-up if 50+) |
| Employee deferral | None | Up to $24,500 in 2026 |
| Employer contribution | Up to 25% of compensation | Up to 25% of compensation |
| Catch-up (age 50+) | No | $8,000 ($11,250 if age 60–63) |
| Roth option | Limited, depends on provider | Yes, Roth employee deferrals |
| Can take a loan | No | Yes, up to plan limits |
| Annual paperwork | None | Form 5500-EZ once assets top $250,000 |
| Setup difficulty | Very easy | Moderate |
The figures above come from the IRS 2026 cost-of-living limits in Notice 2025-67. Now here is how each account actually works.
How a SEP IRA works in 2026
A SEP IRA is an employer-funded retirement plan where you, as your own boss, contribute the lesser of 25% of your compensation or the annual maximum contribution, which is $72,000 for 2026. There is no separate employee contribution. The whole thing is one employer deposit. The IRS sets the 2026 SEP contribution limit at $72,000 and the compensation cap that feeds the math at $360,000. It is built for self-employed individuals and small business owners who want a high ceiling with no plan administration.
If you are self-employed rather than paid a W-2 salary, the 25% rate works out to roughly 20% of your net self-employment earnings, because the calculation backs out half your self-employment tax and the contribution itself. That makes your net income the number that matters. The IRS publishes the exact rate worksheet in Publication 560, so run your real figure there or with your tax pro. A quick example: on about $60,000 of net income from self-employment, your SEP contribution lands near $11,000 to $12,000, and the whole amount is tax-deductible.
The catch with a SEP is the employee rule. If your business has eligible employees, you generally have to contribute the same percentage of pay for them as you do for yourself. For a true solo operator that never matters. The moment you hire, it can get expensive fast. SEP contributions are traditionally pre-tax and grow tax-deferred until withdrawals become taxable in retirement, and you can open a SEP-IRA at almost any brokerage in a few minutes with no annual filing required.
How a Solo 401(k) works in 2026
A Solo 401(k), which the IRS calls a one-participant 401(k), lets you contribute as both the employee and the employer, which is why it usually beats a SEP on total savings. As the employee you can defer up to $24,500 of pay in 2026. As the employer you can add a profit-sharing contribution of up to 25% of compensation on top. The combined total still cannot exceed the $72,000 annual contribution limit the IRS sets for 2026, but you reach that ceiling at a much lower income than a SEP allows. It is the strongest retirement plan for self-employed business owners with no staff.
Two extras make the Solo 401(k) stronger for a lot of people. First, catch-up contributions. If you are 50 or older you can add another $8,000 in 2026, and if you are age 60 to 63 the catch-up rises to $11,250, both on top of the $72,000 limit. A SEP has no catch-up at all. Second, the Roth option and the flexibility it brings. A Solo 401(k) lets you split between traditional pre-tax and Roth elective deferrals, so you choose whether the money is taxable now or tax-free later. That is a real lever a SEP usually does not give you.
The trade-off is effort. A Solo 401(k) is only for a business with no employees other than a spouse, and you usually have to establish the plan by December 31 to contribute for that tax year. Once the account tops $250,000 in assets, the IRS requires a short Form 5500-EZ each year. Most major brokerages offer free Solo 401(k) plans, but you do the setup once and file that form later. For a one-person business chasing the biggest tax-deductible deduction, that extra paperwork is usually worth it.
SEP IRA vs Solo 401k: contribution limits compared
At the same income, a Solo 401(k) almost always lets you contribute more, because it stacks a flat employee deferral on top of the employer percentage. Picture a freelancer with about $60,000 of net self-employment income. With a SEP, the contribution is roughly 20% of that, near $12,000. With a Solo 401(k), that same person can defer $24,500 as the employee and add the same roughly $12,000 as the employer, for a total around $36,500. Same income, three times the tax-advantaged savings.
The gap only closes at higher income. To hit the full $72,000 with a SEP, you need compensation around $288,000, since 25% of that is $72,000. A Solo 401(k) gets you there far sooner because the $24,500 employee deferral does not depend on a percentage, and the additional catch-up can push your total even higher. So the lower your income, the bigger the Solo 401(k) advantage. At very high income, both land at the same $72,000 ceiling and the choice comes down to simplicity versus the Roth and catch-up features.
When a SEP IRA is the better choice
A SEP IRA wins when you want the simplest possible account and you are not trying to squeeze out the absolute maximum. Pick a SEP when:
- You want zero paperwork. A SEP has no annual IRS filing, ever, no matter how big it gets.
- You opened it at the last minute. You can set up and fund a SEP up to your tax filing deadline, including extensions, for the prior year.
- Your income is high and steady. If you earn enough that 25% already maxes you out, the Solo 401(k) edge mostly disappears.
- You might add staff later. A SEP scales to employees, though you then owe them the same percentage.
When a Solo 401(k) wins
A Solo 401(k) wins when you want to save the most on a modest or mid-range income, or you want a Roth bucket. Pick a Solo 401(k) when:
- You want to contribute more at the same income. The flat $24,500 employee deferral does the heavy lifting.
- You are 50 or older. The $8,000 catch-up ($11,250 at age 60 to 63) only exists on the 401(k) side.
- You want Roth money. Roth employee deferrals let you lock in tax-free growth.
- You have no employees. A spouse is fine, but anyone else generally rules it out.
How to open a SEP IRA or Solo 401(k)
Opening either account is straightforward, and most large brokerages offer both with no setup or annual fee. Here is the path.
- Confirm you have self-employment income. Freelance, 1099, or small-business profit all count. A side hustle counts too.
- Pick the account that fits. Use the comparison above. No employees and want the max? Solo 401(k). Want dead-simple? SEP.
- Open it at a brokerage. Major firms like Fidelity, Schwab, and Vanguard offer free SEP and Solo 401(k) accounts. Choose low-cost index funds for your investment inside it.
- Calculate your contribution. Use the Publication 560 worksheet or your tax software so you do not over-contribute.
- Fund it before the deadline. Employer contributions can go in up to your filing deadline plus extensions. A Solo 401(k) usually needs to be established by year end.
This is general information, not individual tax advice. Your exact contribution depends on your net earnings and your full tax picture, so confirm the numbers with a tax pro before you file.
Conclusion: which one should you open?
If you run a one-person business and want to save the most, open a Solo 401(k). If you want the simplest account with no annual filing, open a SEP IRA. Both shelter up to $72,000 in 2026, both cut your tax bill, and both beat doing nothing while your profit sits idle. The best account is the one you actually fund, every year, with low-cost index funds inside it. Keep building from here with our guides on saving for retirement when you are self-employed, how to buy index funds, and the quiet power of compound interest. If quarterly taxes are part of your life now, our walkthrough on how to pay quarterly estimated taxes pairs well with this. For more, browse the full retirement section.
