Determines how the employer contribution is calculated.
Net earnings from self-employment (Schedule C / K-1). Capped at $360,000 (401(a)(17)).
Maximum: $24,500
Contribution Breakdown
20% of net self-employment earnings
Capped by 415(c) limit of $72,000.
2026 Annual Limits
Traditional Contributions
- Tax-deductible now
- Reduces current taxable income
- Taxed in retirement
- RMDs required at age 73
Roth Contributions
- After-tax contributions
- No current tax deduction
- Tax-free withdrawals in retirement
- No RMDs during the owner's lifetime
How the Solo 401(k) calculator works
A Solo 401(k) lets an owner-only business contribute in two roles. You enter your business type, your net business profit or W-2 wages, and your age. The calculator then applies the employee deferral limit, the employer contribution percentage that matches your business type, and the combined annual limit.
Employee contribution
As the employee, you may defer up to the annual elective deferral limit, or your compensation if it is lower. Participants age 50 and older may add a catch-up amount, with a higher catch-up amount at ages 60 through 63.
Employer contribution
As the employer, the business may contribute up to 25% of W-2 wages. For an unincorporated business, the equivalent calculation is 20% of net earnings after the deductible portion of self-employment tax, which is why the two business types produce different results from the same income figure.
Total estimated contribution
Employee and employer contributions together are subject to one combined annual additions limit, with catch-up contributions counted separately. The total shown is an estimate based only on the figures you enter.
Important limitations
This calculator is educational only. It does not provide individualized financial, tax, investment or legal advice. Results depend entirely on the figures you enter and do not reflect fees, taxes, market performance, plan-document terms, other retirement plans, controlled-group rules or state considerations. Self-employment figures use an approximation of the deductible half of self-employment tax and do not model the Medicare-only rate above the Social Security wage base. Confirm any figure with your own tax adviser before acting on it.
Last reviewed September 2026. Figures are from the IRS and depend on your individual facts. See the IRS 2026 limits.
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