As a 1099 gig worker — whether you drive for DoorDash, freelance on Upwork, or run your own consulting business — you don't have access to a company 401k. That means retirement savings are 100% on you. The good news: self-employed workers have access to two of the most powerful retirement vehicles available, and either one can slash your tax bill by thousands of dollars each year.
Here's the one-sentence take: At lower incomes, a SEP-IRA is simpler and nearly identical. At higher incomes ($70K+), a Solo 401k pulls ahead with higher contributions and a Roth option. But the full story matters — read on.
| Feature | SEP-IRA | Solo 401k |
|---|---|---|
| 2026 Max Contribution | $70,000 | $70,000 |
| Employer Contribution | 25% of net SE income | 25% of net SE income |
| Employee Deferral | Not available | $23,500 (2026 projected) |
| Catch-Up (50+) | None | $7,500 extra |
| Roth Option | No (Traditional only) | Yes |
| Setup Deadline | Tax filing deadline + extensions | December 31 of tax year |
| Paperwork | Minimal (1-page form) | Moderate (plan document) |
| Form 5500 Filing | Never required | Required if balance >$250K |
| Loans | Not allowed | Up to $50K or 50% of balance |
| Employees Allowed? | Yes | No (except spouse) |
A Simplified Employee Pension (SEP-IRA) is a retirement plan where you — acting as the employer — contribute to a traditional IRA on behalf of yourself (the employee). It's the simplest retirement plan for self-employed people, requiring little more than opening an account and writing a check.
The contribution formula for a self-employed person is 25% of net self-employment income (after deducting half of SE tax and the contribution itself — the IRS calls this the "reduced rate," which works out to roughly 20% of net Schedule C income in practice). In 2026, the maximum you can contribute is $70,000.
Key Point: If you have employees, you must contribute the same percentage of their compensation that you contribute for yourself. For solo operators, this is irrelevant — but it's a dealbreaker for anyone with staff.
Example: If your net Schedule C income is $100,000, your SEP-IRA contribution would be approximately $20,000 (20% of net income after the circular calculation). You deduct that $20,000 from your taxable income, saving $4,400–$5,000 at 22–25% marginal rates.
A Solo 401k (also called an Individual 401k or Uni-K) is a 401k plan designed for business owners with no employees other than a spouse. It gives you two contribution channels:
The combined limit for both channels is $70,000 in 2026. For workers aged 50+, the employee deferral cap rises to $31,000 (including a $7,500 catch-up), pushing the total possible to $77,500.
Why the dual channel matters: The employee deferral lets you contribute a fixed dollar amount regardless of income percentage. At $50K net income, a SEP-IRA gets you ~$10,000 — but a Solo 401k lets you put in $23,500 as the employee plus ~$10,000 as the employer, for $33,500 total. That's a game-changer at lower and mid incomes.
To see exactly where each plan shines, here's the math at different net self-employment income levels. The SEP-IRA contribution is approximately 20% of net SE income (the exact rate after the circular deduction). For the Solo 401k, we show the max: employee deferral up to $23,500 plus 25% employer contribution — capped at $70,000 total.
| Net SE Income | SEP-IRA Max | Solo 401k Max | Winner |
|---|---|---|---|
| $30,000 | ~$5,575 | ~$29,075 | Solo 401k (+$23,500) |
| $50,000 | ~$9,290 | ~$32,790 | Solo 401k (+$23,500) |
| $75,000 | ~$13,935 | ~$37,435 | Solo 401k (+$23,500) |
| $100,000 | ~$18,585 | ~$42,085 | Solo 401k (+$23,500) |
| $150,000 | ~$27,865 | ~$51,365 | Solo 401k (+$23,500) |
| $200,000 | ~$37,160 | ~$60,660 | Solo 401k (+$23,500) |
| $280,000 | ~$52,000 | $70,000 (capped) | Solo 401k |
| $350,000 | $70,000 (capped) | $70,000 (capped) | Equal |
As the table shows, the Solo 401k dominates at every income level below ~$350K because the $23,500 employee deferral is pure upside. Only at very high incomes — where 25% of compensation already hits the $70K cap — do the two plans converge.
Both plans offer traditional (pre-tax) contributions that reduce your current-year taxable income. This is the default for SEP-IRAs and an option for Solo 401ks.
But the Solo 401k has a feature the SEP-IRA doesn't: a Roth option. With Roth contributions, you pay tax now but withdrawals in retirement are completely tax-free — including decades of investment growth.
Roth vs Traditional — which to choose? If you expect to be in a higher tax bracket in retirement, Roth wins. If you expect to be in a lower bracket, Traditional wins. For many gig workers in the 12–22% brackets, splitting between both (Traditional employer profit-sharing + Roth employee deferral in a Solo 401k) provides tax diversification.
SEP-IRAs are always traditional — you take the deduction now and pay ordinary income tax on withdrawals. There is no Roth SEP-IRA. If you want Roth treatment on any portion of your self-employed retirement savings, the Solo 401k is your only option between these two plans.
One area where the SEP-IRA wins is deadline flexibility:
Planning tip: If you're reading this in, say, March 2027 and want to reduce your 2026 taxes, a SEP-IRA is still available to you. A Solo 401k is not — you'd need to wait for the 2027 tax year. This is the SEP-IRA's strongest tactical advantage.
The Solo 401k is dramatically better. At $40,000 net income, a SEP-IRA lets you contribute ~$7,400. A Solo 401k lets you contribute $23,500 (employee) + ~$7,400 (employer) = ~$30,900. That's over 4x more. Even if you can't max it out, the flexibility is unmatched.
Solo 401k still wins on contribution capacity. That said, if you value simplicity and don't expect to contribute more than 20% of income, the SEP-IRA is adequate. Many freelancers in this range use a SEP-IRA simply because it's less paperwork.
The Solo 401k's employee deferral still provides a significant edge. You also begin to benefit from the Roth option — at higher incomes, being able to stuff $23,500 into Roth each year is a powerful long-term wealth-building strategy.
At very high incomes, both plans cap at $70,000, so they're functionally identical on contribution limits. The choice comes down to Roth availability (Solo 401k) vs. simplicity (SEP-IRA).
Let's see the actual tax savings from maxing out each plan. We'll use projected 2026 marginal rates for single filers (pre-TCJA reversion: 15% on $11,601–$47,150, 25% on $47,151–$100,525, 28% on $100,526–$191,950).
| Scenario | Net SE Income | SEP-IRA Max | Tax Saved (SEP) | Solo 401k Max | Tax Saved (Solo) |
|---|---|---|---|---|---|
| Part-time gig worker | $50,000 | ~$9,290 | ~$1,394 | ~$32,790 | ~$4,919 |
| Full-time freelancer | $100,000 | ~$18,585 | ~$3,252 | ~$42,085 | ~$7,365 |
| High-earning contractor | $150,000 | ~$27,865 | ~$5,573 | ~$51,365 | ~$10,273 |
Tax savings assume contributions fall within the marginal bracket. Actual savings depend on your specific tax situation.
Over 20 years, the Solo 401k's extra contribution capacity compounds to hundreds of thousands of dollars more in retirement savings — even before considering the tax-free growth of the Roth portion.
Use our free 1099 tax calculator to model your self-employment income, deductions, and retirement contributions — all in one place.
Try the 1099 Tax Calculator →Form 5500-EZ penalty: If your Solo 401k balance exceeds $250,000 and you forget to file Form 5500-EZ, the IRS penalty is $250 per day, capped at $150,000. Set a calendar reminder.
If you're 50 or older, the Solo 401k offers a clear advantage: a $7,500 catch-up contribution on top of the $23,500 employee deferral limit. That pushes your total employee contribution to $31,000 and your combined max to $77,500.
The SEP-IRA has no catch-up provision. The $70,000 cap is the same regardless of age. For older workers trying to accelerate retirement savings, this alone can make the Solo 401k the better choice.
Technically, yes — you can maintain both a SEP-IRA and a Solo 401k. However, the employer contribution cap is shared (25% of compensation across all plans), making dual plans redundant for most solo operators. If you already have a SEP-IRA and want to switch to a Solo 401k, you can roll the SEP-IRA balance into the Solo 401k and close the SEP.
For the vast majority of 1099 workers, the Solo 401k is the better plan. It allows higher contributions at every income level below ~$350K, offers a Roth option, includes catch-up contributions, and lets you take loans against your balance.
The SEP-IRA wins on exactly one dimension: deadline flexibility and simplicity. If you need to make a last-minute contribution for the prior tax year or you want the absolute minimum paperwork, the SEP-IRA is still an excellent choice — and infinitely better than saving nothing.
Either way, the most important move is to open one and start contributing. The tax savings alone often fund a significant portion of the contribution, and the compounding growth over decades dwarfs any difference between the two plans.
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