Retirement plan comparisons for the self-employed usually assume a one-person business. The moment you hire even a single part-time employee, the calculus shifts, because both a SEP IRA and a SIMPLE IRA come with rules about what you owe your staff, not just yourself.
The SEP IRA's hidden cost once you have employees
A SEP IRA is entirely employer-funded, and the IRS requires you to contribute the same percentage of compensation for every eligible employee that you contribute for yourself. Contribute 20% of your own compensation, and you generally must contribute 20% of compensation for each eligible employee too — a rule solo freelancers never think about, since it never applied to them until they hired someone.
How a SIMPLE IRA works instead
A SIMPLE IRA lets employees make their own salary-deferral contributions, similar to a 401(k), while requiring the employer to either match employee contributions up to a set percentage or make a smaller fixed contribution for all eligible employees regardless of whether they defer anything themselves. The overall contribution limits are lower than a Solo 401(k) or SEP IRA, but the employer-side cost is generally more predictable and often smaller than matching a SEP IRA's percentage-of-pay requirement.
A side-by-side view
A SEP IRA suits a freelancer who occasionally uses subcontractors properly classified as independent contractors (who don't count as 'employees' for this purpose), keeping the business effectively one-person for retirement plan purposes. A SIMPLE IRA tends to suit a small but genuine team — a part-time assistant, an office manager, a couple of true W-2 employees — where sharing a percentage-of-pay SEP contribution across payroll would get expensive fast.
Don't confuse a contractor with an employee here
This entire comparison hinges on correctly classifying the people who work with you. Properly classified independent contractors you pay via 1099 do not count as 'employees' for either plan's coverage rules — but misclassifying someone who should legally be a W-2 employee can retroactively blow up your SEP IRA's compliance, on top of the separate legal and payroll tax problems misclassification creates.
Frequently asked questions
Can I have a SIMPLE IRA and a Solo 401(k) at the same time?
Generally no — you can't maintain a SIMPLE IRA alongside another qualified retirement plan for the same business in the same year, which is part of why the choice matters before you commit to one.
What if I only have one part-time employee?
Even one eligible part-time employee can trigger the SEP IRA's equal-contribution-percentage requirement, so it's worth running the math on both plans before assuming a SEP IRA is still the simpler choice.
Does hiring an independent contractor trigger these employer contribution rules?
No — properly classified independent contractors paid via 1099 are not 'employees' for retirement plan coverage purposes, so hiring contractors alone does not create an employer contribution obligation under either plan.