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Solo 401(k) eligibility checker

A solo 401(k) is not a product choice — it is a coverage definition. Answer six questions and get a plain-words verdict from the IRS one-participant rules, then the calculator that sizes the contribution if the plan fits.

1. Do you have self-employment income — or own the business that would sponsor the plan?
Carried into the calculator link below, so the calculator opens on the right path.
3. Does the business employ anyone other than you?
4. If other people work in the business, how do their hours look? (Skip this if you answered just me or only my spouse above — the verdict ignores it then.)
5. Has any part-time worker reached 500 hours or more in each of two years in a row?
Optional, and not part of the verdict — it only pre-fills the calculator at the end. Eligibility turns on who is covered, not on the amount.

Your verdict

Answer the questions above

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Open the Solo 401(k) Calculator

Estimate only — not a determination. This verdict applies the IRS one-participant coverage rules stated below to the answers you gave. It is not tax or retirement advice, and it cannot see plan documents, related businesses, or an employee's full history. Confirm eligibility with a plan provider or tax professional before adopting a plan.

Last updated: October 27, 2026

This checker decides one question: whether a one-participant (solo) 401(k) fits your business at all. It does not size a contribution — the Solo 401(k) Calculator at the end does that — and it does not compare a solo 401(k) against a SEP or SIMPLE plan. What it does is apply the IRS coverage definition to the facts that decide it: self-employment income to stand on, and who else works in the business.

How this verdict works

The rules below are the whole logic of the checker — the verdict implements them exactly as stated, and each rule names its primary source.

  • Coverage defines the plan. A one-participant 401(k) plan is a traditional 401(k) plan covering a business owner with no employees, or that person and their spouse. (IRS, One-participant 401(k) plans.)
  • Self-employment income is the base. For a self-employed individual, contributions are figured on earned income — net earnings from self-employment after deducting one-half of self-employment tax and the contributions made for yourself — worked out with the rate table and worksheets in Chapter 5 of IRS Publication 560. (Same IRS page; Publication 560.)
  • Other employees end the solo form. A business owner with no common-law employees needs no nondiscrimination testing; that advantage vanishes if the employer hires employees, and employees who meet the plan eligibility requirements must be included in the plan. (Same IRS page.)
  • The full-time line. A plan generally cannot require, as a condition of participation, more than a year of service — a 12-month period in which the employee completes at least 1,000 hours. An employee over that line is an employee who must be counted. (IRS Publication 560, Restriction on conditions of participation.)
  • The part-time wrinkle (caveat, applied as a borderline flag). For plan years beginning after 2024, a 401(k) plan also cannot require, as a condition of participation, a period of service extending beyond the first period of two consecutive 12-month periods (excluding periods beginning before 2021) in each of which the employee completed at least 500 hours of service. A part-time worker over that line may have to be allowed to make elective deferrals even though they never reach 1,000 hours — which is why this checker answers borderline, not eligible, whenever that pattern appears or cannot be ruled out. (IRS Publication 560, same section; the two-period figure is the SECURE 2.0 reduction of the original three-period rule.)

Rule sources: IRS, “One-participant 401(k) plans,” https://www.irs.gov/retirement-plans/one-participant-401k-plans and IRS Publication 560, Retirement Plans for Small Business, https://www.irs.gov/publications/p560 — checked October 27, 2026.

Reading the verdict

Appears eligible means the answers match the IRS coverage definition: self-employment income (or your own business), and no employees other than you and a spouse, with no part-time pattern that trips the 500-hour line. Likely not means an answer contradicts the definition — no self-employment income, or an employee at 1,000 hours or more. Borderline means the deciding fact is one this form cannot settle: unknown hours, a two-year 500-hour pattern, or a partnership or other structure where who counts as an employee needs the plan documents. No verdict on this page is a guarantee of eligibility.

Estimates for planning only. This checker is not tax, retirement, or legal advice, and using it does not create a professional relationship. Verify eligibility against the IRS sources above or with a qualified professional before adopting or funding a plan.

Frequently asked questions

What makes a 401(k) a solo 401(k)?

It is a traditional 401(k) plan covering a business owner with no employees, or that owner and their spouse — the IRS calls it a one-participant 401(k) plan. It follows the same rules as any other 401(k) plan; what makes it solo is who is covered. Once other employees must be included, it is no longer a one-participant plan.

Can my spouse count without ending the solo plan?

Yes. The IRS definition covers the business owner and their spouse, so a spouse who works in the business does not by itself end one-participant status. Other employees are the deciding fact — if they meet the plan eligibility requirements, they must be included, and the no-testing advantage of the one-participant plan vanishes.

I work part-time help only a few hours a week. Is the plan still solo?

Possibly — that is the borderline case this checker flags rather than settles. A plan generally cannot require more than a year of service (a 12-month period with at least 1,000 hours) as a condition of participation, and for plan years beginning after 2024 it also cannot require service beyond two consecutive 12-month periods with at least 500 hours in each as a condition of making elective deferrals. A long-term part-time worker over those lines may have to be included even though no one reaches 1,000 hours.

Do I need self-employment income for a solo 401(k)?

Yes, in the form the plan requires: contributions are figured on compensation, which for a self-employed individual is earned income — net earnings from self-employment after deducting one-half of self-employment tax and the contributions for yourself. With no self-employment earnings and no business of your own, there is no compensation for a one-participant plan to stand on.

Does a yes here guarantee I can open a solo 401(k)?

No. The verdict applies the IRS coverage rules to the answers given and says appears eligible, not eligible. Plan documents, controlled-group and related-business facts, and an employee history a short form cannot see can all change the answer. Confirm with a plan provider or tax professional before adopting a plan.