SEP vs. Solo 401(k) vs. SIMPLE

Self-employed? Three plans allow very different contributions. See which lets you save the most.

Your numbers

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Highest contribution

Best plan for you
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We adjust net profit for the deductible half of self-employment tax, then apply each plan's rules for 2025: a SEP-IRA and the employer side of a Solo 401(k) allow about 20% of adjusted profit; a Solo 401(k) adds an employee deferral of 23,500 (7,500 catch-up at 50+); a SIMPLE IRA allows a 16,500 deferral (3,500 catch-up) plus a 3% employer match. All are capped by the annual additions limit. Estimates only; confirm with a tax advisor.
About this calculator

SEP vs. Solo 401(k) vs. SIMPLE

Estimates your 2025 maximum retirement contribution under a SEP IRA, a Solo 401(k), and a SIMPLE IRA using your self-employment profit and age.

How the contributions are figured

The tool first reduces your net self-employment profit by half of your self-employment tax, then applies each plan's formula. A SEP IRA or the employer piece allows roughly 20% of that adjusted profit, while a Solo 401(k) adds a 23,500 employee deferral on top, plus a 7,500 catch-up if you are 50 or older. A SIMPLE IRA permits a 16,500 deferral with a 3,500 catch-up, plus a 3% match.

Choosing among the plans

For many solo earners the Solo 401(k) allows the largest total because it stacks the deferral and the employer contribution. SEP IRAs are simple to open but rely only on the profit-based percentage, and SIMPLE IRAs generally allow the least at higher incomes. Overall dollar caps and plan rules apply, so confirm exact limits with a tax professional; these are estimates, not tax advice.

How to use it

  1. Enter your net self-employment profit.
  2. Enter your age so catch-up eligibility is applied.
  3. Review the estimated SEP, Solo 401(k), and SIMPLE maximums.
  4. Compare the totals to pick the plan that fits your situation.

Frequently asked questions

Which plan lets me save the most?

For most self-employed people with meaningful profit, the Solo 401(k) allows the highest contribution because it combines a salary deferral with an employer contribution. SEP and SIMPLE plans usually trail at the same income.

Can I still contribute if I have a day job?

Yes, but your 23,500 employee deferral limit is shared across all 401(k) plans, including an employer's. The employer or profit-based portion is calculated separately per business.

Are these figures exact?

No, they are estimates using 2025 limits and standard formulas. Your accountant should confirm the amounts before you fund a plan.

See the exact formula and a worked example on our methodology page.

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