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Retirement Accounts for a One-Person Business
Compare SEP-IRA, one-participant 401(k), and personal IRA options using 2026 limits, self-employed contribution math, deadlines, Roth features, and future-employee consequences.
A SEP-IRA, one-participant 401(k), and personal traditional or Roth IRA use different contribution rules, deadlines, tax treatment, and administrative requirements. The highest headline limit is not automatically the best plan. For 2026, the 401(k) employee elective-deferral limit is $24,500 and the IRA contribution limit is $7,500, subject to eligibility and catch-up rules. The defined-contribution/SEP ceiling is $72,000 before catch-up, again subject to compensation calculations.
Solo 401(k) math has employee and employer sides
A one-participant 401(k) lets an eligible business owner contribute in both employee and employer capacities, but self-employed employer-contribution math is not simply 25% of Schedule C profit. IRS Publication 560 shows the calculation.
2026 solo retirement-plan comparison
| Plan type | Compare a traditional or Roth IRA, SEP-IRA, and one-participant 401(k) by contribution capacity, Roth needs, administration, deadlines, future employees, and plan-provider cost—not by headline maximum alone. |
|---|---|
| 2026 limit | Use current IRS limits: $24,500 for 401(k) elective deferrals, $7,500 for IRAs, and a $72,000 defined-contribution ceiling before applicable catch-up amounts and subject to compensation rules. |
| Contribution role | A one-participant 401(k) can involve employee and employer contributions. Self-employed employer-contribution math adjusts for the contribution deduction and is not simply 25% of Schedule C profit. |
| Admin tradeoff | Check plan document fees, investment costs, Form 5500-EZ thresholds/requirements, establishment deadlines, and what happens if employees become eligible. The best plan is the one the business can operate correctly. |
SEP simplicity comes with employer-contribution rules
A SEP is administratively simple and employer-funded, but it does not offer the same employee-deferral mechanics as a solo 401(k). If you later add eligible employees, SEP contribution rules can create obligations for them too.
An IRA remains a separate account with its own eligibility rules
Traditional and Roth IRA eligibility and deductibility depend on income and workplace-plan coverage. Having a solo business does not create a separate unlimited IRA bucket.
S-corp retirement contributions depend on W-2 compensation
If your business is an S corporation, retirement-plan contributions generally rely on W-2 compensation, not shareholder distributions. That makes reasonable-salary and retirement planning connected decisions.
A $20,000 retirement target in 2026
2026 comparison example: a solo operator who wants to save $20,000 may not need the complexity of optimizing every plan limit. Another with much higher net earnings and a goal of maximizing tax-advantaged savings may value the employee-plus-employer mechanics of a one-participant 401(k). Calculate the allowed amount from current IRS rules before funding. The plan comparison should also record whether the business expects to hire an eligible employee, whether Roth contributions matter, whether a loan feature is useful, what the custodian charges, and whether Form 5500-EZ may eventually be required. Those operating details can change the best answer even when two plans allow the same target contribution for the current year.
Contribution math that changes with business structure
A SEP-IRA, one-participant 401(k), and personal IRA do not have interchangeable contribution mechanics. For 2026, the employee elective-deferral limit for 401(k)-type plans is $24,500 and the IRA contribution limit is $7,500, before applicable catch-up rules. The overall defined-contribution/SEP limit is $72,000 for 2026, subject to compensation and plan rules. A one-participant 401(k) can combine employee deferrals with employer contributions, while a SEP is employer-funded. Self-employed employer-contribution math is adjusted for the deduction for the contribution and is not simply 25% of Schedule C net profit.
Do not choose only by the headline maximum. Compare plan-document or platform fees, investment choices, Roth features, loan availability, tax-filing requirements, establishment and contribution deadlines, and what happens if you hire an eligible employee. An S-corporation owner's plan contributions generally key off W-2 compensation rather than shareholder distributions, which can change the comparison materially. IRS limits are indexed and deadlines can change under law, so reopen the current-year IRS pages before funding. If the goal is simply to save $10,000 or $20,000, the administratively simplest plan may be enough; optimization matters more when contribution capacity, Roth treatment, or future staffing makes the differences consequential.
Compare retirement accounts by contribution mechanics and administration, not just the headline maximum. An IRA is individual and relatively simple but has a lower annual contribution limit. A SEP-IRA generally uses employer contributions and can be straightforward for a solo business, but adding eligible employees changes the economics because the same contribution percentage rules can apply. A one-participant or Solo 401(k) can combine employee elective deferrals with employer contributions subject to the plan and tax limits, which can create more contribution room at some income levels. For 2026, the IRS elective-deferral limit for 401(k) plans is $24,500 and the IRA limit is $7,500; the defined-contribution total limit is $72,000 before applicable catch-up amounts. Eligibility and compensation calculations still control what a particular owner can contribute.
Put deadlines and future staffing on the worksheet. A plan that is ideal for a one-person business can require a different setup when common-law employees become eligible. Solo 401(k)s also bring plan documents, deposit timing, and possible Form 5500-EZ filing once plan assets reach the applicable threshold or at termination. SEP contributions use business-income formulas that differ for self-employed individuals from a simple employee salary percentage. If the business is taxed as an S-corporation, owner W-2 compensation matters to plan contributions. Before moving large amounts, model current-year cash needs, emergency reserves, tax payments, and expected profit; retirement tax benefits are not a reason to create a cash crisis. Verify limits and deadlines on the IRS plan page for the contribution year and ask the plan provider or tax professional to check the self-employed compensation calculation.
Before opening or funding a solo plan
- Confirm business entity and compensation type.
- Set the 2026 savings target before choosing a plan.
- Check employee and employer contribution formulas.
- Review deadlines and future-employee consequences.
- Coordinate contributions with a CPA/EA and plan provider.
Retirement-plan questions for a one-person business
What are the main 2026 limits I should know?
For 2026, the 401(k) elective-deferral limit is $24,500, the IRA contribution limit is $7,500, and the defined-contribution / SEP maximum is $72,000 subject to the plan rules and compensation limits. Catch-up rules add separate amounts for eligible participants.
Why is a solo 401(k) different from a SEP-IRA?
A one-participant 401(k) can combine an employee elective deferral with an employer contribution, while a SEP is employer-funded and follows a different contribution formula. The better fit depends on income, desired contribution, administrative tolerance, entity/compensation form, and whether eligible employees may appear later.
Can a self-employed person just contribute 25% of Schedule C profit to a SEP?
Not directly. For self-employed owners, the employer-contribution calculation is adjusted for the deduction for one-half of self-employment tax and the contribution itself, so the effective rate differs from the simple employee-compensation percentage. Use the IRS self-employed worksheet or a professional calculation.
What if I also have a 401(k) at a W-2 job?
Employee elective deferrals are generally aggregated across plans for the annual limit, while employer contributions can follow plan-specific rules. A second plan does not create a second personal deferral limit. Coordinate contributions before year end so a side-business plan does not accidentally create an excess deferral.