Once you’re self-employed, no employer is going to auto-enroll you in a 401(k) or match your contributions. Building a retirement fund becomes entirely your responsibility, but the tax code also hands freelancers some of the most generous retirement accounts available — if you pick the right one. The two most common options are the SEP-IRA and the Solo 401(k). Here’s how they actually differ and how to decide between them.
The short version
A SEP-IRA is simpler to open and maintain, but contributions are limited to a percentage of your net self-employment income. A Solo 401(k) is more paperwork to set up, but it lets most freelancers contribute significantly more at the same income level, because it combines an “employee” contribution with an “employer” contribution. If your business has no employees other than you (and possibly a spouse), both are on the table.
How a SEP-IRA works
A Simplified Employee Pension IRA lets you contribute a percentage of your net self-employment earnings, up to an annual dollar cap that the IRS adjusts each year. There’s no employee salary-deferral component — the entire contribution is treated as an “employer” contribution calculated from your business income. Setup is usually a single form with a brokerage, and many providers will open one online in under fifteen minutes with no ongoing filing requirements.
How a Solo 401(k) works
A Solo 401(k) — also called an individual 401(k) — lets you contribute in two capacities. As the “employee,” you can defer a portion of your compensation up to the standard employee deferral limit (with an extra catch-up amount if you’re 50 or older). As the “employer,” you can then add a profit-sharing contribution calculated as a percentage of your net self-employment income. Stacking both often lets you shelter considerably more money than a SEP-IRA at the same income level, especially for freelancers with moderate income. Many Solo 401(k) plans also allow loans against the balance and a Roth (after-tax) option, which SEP-IRAs typically don’t offer.
Where a SEP-IRA wins
- Simplicity: one form, no annual filing, and most brokerages set it up for free.
- Good fit if your income is high enough that the contribution caps aren’t binding, since both accounts hit the same overall dollar ceiling at higher incomes.
- Better if you might hire employees soon — a SEP-IRA generally requires you to contribute the same percentage for eligible employees, which is simple to administer at a small scale.
Where a Solo 401(k) wins
- Moderate income: the employee deferral component lets you contribute more than a SEP-IRA would allow at the same earnings level.
- Roth option: if your plan provider offers it, you can contribute after-tax dollars and let growth come out tax-free in retirement.
- Catch-up contributions if you’re 50+, on top of the standard limits.
- Loan provisions, if your provider allows them and you want that flexibility (generally not advisable as a first resort, but useful to know it exists).
The paperwork trade-off
A Solo 401(k) requires a formal plan document when you open it, and once your account balance crosses a certain threshold, you’ll need to file a short annual form (Form 5500-EZ) with the IRS. A SEP-IRA has neither requirement. If you want the highest contribution ceiling with the least ongoing administration, that’s the central trade-off to weigh.
A simple way to decide
If your net self-employment income is modest and you want to save aggressively, run the numbers on a Solo 401(k) first — the employee deferral component usually lets you shelter more. If you value simplicity above maximizing the contribution ceiling, or you’re not sure how consistent your income will be, a SEP-IRA is easier to open, easier to skip contributing to in a lean year, and easier to close if your business changes direction. Both allow you to open and fund the account up until your tax filing deadline (including extensions) for the prior year, which gives you time to see how the year actually turned out before committing money.
Key takeaways
- A SEP-IRA is simpler and contribution-only; a Solo 401(k) usually allows higher contributions at moderate income through its dual employee/employer structure.
- Solo 401(k)s can offer a Roth option and loan provisions that SEP-IRAs generally don’t.
- SEP-IRAs have no annual filing requirement; Solo 401(k)s require a filing once the balance passes a certain threshold.
- You can usually open and fund either account up until your tax deadline for the year, so there’s no need to decide mid-year under pressure.
This article is for general educational purposes and isn’t personalized financial or tax advice. Contribution limits and rules change and can vary by provider, so confirm current details with the IRS, a financial advisor, or your plan provider before opening an account.