Solo 401(k) contribution calculator
Self-employed without W-2 employees gets the most generous retirement plan in the US tax code: the Solo 401(k). Contribute as both employee and employer up to the 2026 §415(c) annual additions limit ($72,000).
Employee deferral
$24,500
2026 limit: $24,500
Employer side (~20% of net SE)
$18,470
After SE-tax deduction adjustment
Total annual additions
$42,970
Capped at §415(c) $72,000
Approximate immediate federal tax savings
~$10,313/yr
At a 24% federal bracket. Roth contributions don't generate immediate savings but compound tax-free.
Educational estimate. Exact contribution math depends on your full Schedule SE / Schedule C numbers. Confirm with your CPA before contributing.
Want this tied to your real numbers?
Create a free account and we'll plug your profile in automatically — and place this tool inside your full roadmap.
FAQ
- Why is the employer-side rate "20% effective" instead of 25%?
- The IRS allows the employer-side contribution at 25% of "compensation," but for self-employed people compensation is net SE earnings minus the deductible portion of SE tax. After that adjustment, the effective rate on raw net SE earnings is roughly 18.6–20%.
- Mega backdoor Roth?
- If your Solo 401(k) plan document allows after-tax contributions AND in-plan Roth conversion (Fidelity, ETrade, Schwab usually do), you can fund the gap between employee + employer contributions and the §415(c) total cap (~$72k in 2026) as after-tax → Roth. Adds $30k+/yr of Roth space.
- When do I need to open the plan?
- Solo 401(k) plan must be ESTABLISHED by your business's tax filing deadline (often April 15 + extensions). Employee deferrals must be ELECTED by Dec 31 of the plan year. Employer contributions can be made up to the filing deadline.
Related calculators
Educational guidance only. Not legal, tax, or individualized investment advice. We do not recommend individual securities or guarantee outcomes.