Solo 401(k) Calculator: Double-Up Contributions
The self-employed can wear two hats — employee (up to $24,500 deferral) and employer (25% of net earnings) — to hit combined contributions far beyond a normal 401(k).
Solo 401(k) Inputs
How to Use This Solo 401(k) Calculator
Use this tool if you have self-employment income and want to know how much room a Solo 401(k) gives you across both the employee and employer sides.
- Enter net self-employment earnings and age. Age determines whether you qualify for the standard or super catch-up contribution.
- Set the employee contribution and entity type. Schedule C and S-corp income use different employer-side math.
- Review both buckets together. Solo 401(k) value comes from wearing two hats: employee deferral plus employer contribution.
How to Read the Results
Total Contribution
This is the all-in amount you can shelter for the year under the Solo 401(k) rules.
Employee Side
This uses the normal 401(k) employee limit shared across all your workplace plans.
Employer Side
This is the additional self-employed contribution that makes Solo 401(k) so powerful.
Tax Savings
A rough illustration of the current-year deduction value if contributions are made pre-tax.
What to Do Next
How We Reviewed This Tool
Tool-Level Methodology
- Reviewed both the employee-deferral side and the employer-contribution side so self-employed users can see where their total allowable amount actually comes from.
- Checked the self-employment framing against the site's 2026 limit references and the most common owner-only plan scenarios.
- Structured the output around contribution room first, since that is usually the primary question for solo business owners.
Assumption Review
- Actual solo 401(k) contribution limits depend on business entity type, compensation definition, and self-employment tax treatment.
- The tool is a planning calculator and does not replace CPA-level computation for Schedule C, S-corp, or partnership edge cases.
- It should be used to estimate contribution range and compare plan options, not to file business-plan paperwork.
Update Log
- Rechecked 2026 owner-only contribution-limit framing and catch-up references.
- Aligned links with the contribution-limits and growth tools so self-employed users can move from eligibility to long-term planning.
- Refined solo-plan wording to better cover self-employed and individual 401(k) search variants.
Why Solo 401(k) Beats SEP-IRA
For most self-employed earners, a Solo 401(k) allows higher contributions at lower income than a SEP-IRA because the $24,500 employee deferral is not tied to net earnings. A contractor earning $60,000 can put in $24,500 employee + $12,000 employer = $36,500 in a Solo 401(k). The same earnings in a SEP-IRA cap at $12,000.
Schedule C vs S-Corp Contribution Math
- Schedule C (sole prop): Employer contribution is 20% of net SE earnings minus one-half SE tax (effectively ~18.6%).
- S-Corp / W-2: Employer contribution is a clean 25% of W-2 wages — simpler math, often larger contribution at the same take-home.
Solo 401(k) Features
- Roth option. Most custodians (Fidelity, Schwab, E*TRADE) now offer Roth Solo 401(k).
- Loan option. Up to $50,000 or 50% of balance — same as employer 401(k).
- No annual filing until balance exceeds $250,000 (then Form 5500-EZ required).
- Can include spouse if on payroll — doubles the contribution room.
Frequently Asked Questions
What is a Solo 401(k)?
A Solo 401(k), also called an Individual 401(k) or Self-Employed 401(k), is a retirement plan for self-employed individuals and business owners with no employees (other than a spouse). It allows contributions as both employee and employer, dramatically raising the annual limit.
How much can I contribute to a Solo 401(k) in 2026?
Employee side: up to $24,500 ($32,500 with age 50+ catch-up, $35,750 for age 60–63). Employer side: up to 25% of net self-employment earnings. Combined max is $70,000 ($78,000 or $81,250 with catch-up).
Can I have a Solo 401(k) if I have a W-2 job with a 401(k)?
Yes, if you also have self-employment income. The employee $24,500 limit is shared across all 401(k)s, but the employer 25% contribution on self-employment is separate from your W-2 employer's match, so you can often hit a combined $50,000+ per year.
Further Reading
- Reviewed by David Jones
- Limits Updated for 2026 IRS contribution caps
- Formulas Verified quarterly
Review & Methodology
- Reviewed by David Jones (calculator methodology).
- Updated for 2026 IRS contribution limits (refreshed after each annual IRS notice).
- Core calculator formulas are re-tested quarterly; limit-driven logic is checked when IRS guidance changes.
- Educational projections only — not investment, tax, or wealth-management advice. Calculations run locally in your browser.