Solo 401(k) Calculator
Calculate your maximum Solo 401(k) contribution as a self-employed sole proprietor or single-member LLC — employee deferral plus employer profit-sharing, using 2026 IRS limits.
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Additional Details
This Year: Maximum Total Contribution
Estimated • Based on your inputs
Balance at Retirement
$3,231,708.00
Detailed Breakdown
Disclaimer: This calculator provides estimates for informational purposes only. Results should not be considered financial, tax, or legal advice. Consult a qualified professional for your specific situation.
How This Calculator Works
Calculation methodology and assumptions
A Solo 401(k) — for self-employed sole proprietors, single-member LLCs, or partners with no common-law employees other than a spouse — lets the same person contribute in two roles. As "employee," you can defer up to the standard IRS elective-deferral limit ($24,500 for 2026, plus catch-up if 50+). As "employer," you can add a profit-sharing contribution of up to 20% of your net earnings from self-employment (net profit minus the deduction for one-half of self-employment tax) — the self-employed equivalent of the 25%-of-compensation rule for common-law employees, per IRS Publication 560's reduced-rate worksheet. Combined employee + employer contributions are capped at the overall IRC Section 415(c) limit of $72,000 for 2026, plus your age-based catch-up on top.
How to Use This Investment & Retirement Calculator
- 1
Fill in Current Age and Retirement Age
Current Age starts at 40; Retirement Age starts at 65. Replace each one with your own figure.
- 2
Fill in Current Solo 401(k) Balance and Net Self-Employment Income (Schedule C profit)
Current Solo 401(k) Balance starts at $50,000; Net Self-Employment Income (Schedule C profit) starts at $120,000. Replace each one with your own figure.
- 3
Fill in Desired Employee Elective Deferral and Expected Annual Return
Desired Employee Elective Deferral starts at $24,500; Expected Annual Return starts at 7%. Replace each one with your own figure.
- 4
Read the results
The calculator leads with This Year: Maximum Total Contribution and Balance at Retirement, followed by 6 supporting figures.
Example Calculation
What the calculator above works from before you change anything: $120,000 of Schedule C profit, a $24,500 employee deferral, $50,000 already saved and a 7% return, age 40 to 65.
Self-employment tax is 15.3% of 92.35% of profit (12.4% Social Security on up to $184,500 plus 2.9% Medicare). Subtract half of it from profit to get net earnings from self-employment; the employer contribution can be up to 20% of that figure (IRS Publication 560). Here that is $16,955 of tax and $111,522 of net earnings, so the employer share is $22,304; with the $24,500 deferral the first year's total is $46,804, under the $72,000 overall limit.
Result: Repeating that each year at a 7% return, the account reaches $3,231,708 at 65: $1,170,111 paid in and $2,011,597 of growth on top of the $50,000 you start with.
What Affects Your Results
Rate of Return
Even small differences compound massively over time. 7% vs. 8% over 30 years on $100K means a difference of $200K+. Asset allocation drives your expected return.
Time Horizon
Compounding accelerates exponentially. Most of your wealth is generated in the final years — a 30-year investment earns more in its last 5 years than its first 15.
Contribution Consistency
Regular monthly investments (dollar-cost averaging) smooth out market volatility and ensure you're always buying — including during dips when prices are low.
Fees & Expenses
A 1% annual fee vs. 0.1% fee on a $500K portfolio costs you $4,500/year extra. Over 30 years, high fees can consume 25–30% of potential returns. Use low-cost index funds.
Tips & Best Practices
- Start early. Thanks to compounding, $200/month invested from age 25 to 65 at 8% returns grows to ~$700K. Waiting until 35 cuts that to ~$300K — a $400K penalty for the 10-year delay.
- Don't try to time the market. Research consistently shows that time in the market beats timing the market. Missing the 10 best trading days over 20 years can halve your returns.
- Consider tax-advantaged accounts first: 401(k) (especially with employer match), IRA, HSA. These reduce your tax drag — a 25% tax bracket investor keeps more in a tax-deferred account.
- Rebalance annually. If stocks outperform and grow from 80% to 90% of your portfolio, rebalancing back to 80% locks in gains and manages risk.
- Factor in your state's tax treatment of investment income. Some states exempt certain investment income or have lower rates on capital gains.
StateCalc Team
Editorial Team
The StateCalc team builds financial calculators using data from official government sources including the IRS, U.S. Census Bureau, BLS, and state revenue departments. All formulas are validated by an automated test suite and cross-referenced against published data.
Our editorial standardsFrequently Asked Questions
What is the Solo 401(k) contribution limit for 2026?
For 2026, you can defer up to $24,500 as "employee" (plus a $8,000 catch-up at 50+, or $11,250 at ages 60-63). As "employer," you can add up to 20% of your net self-employment earnings. Combined, the overall cap is $72,000 (plus catch-up) — one of the highest contribution ceilings of any retirement account available to the self-employed.
Why is the employer contribution 20% and not 25% of net self-employment income?
The 25% employer-contribution rule applies to common-law employees' W-2 compensation. Because a self-employed person's own contribution is itself deducted from net profit before computing the contribution (a circular calculation), IRS Publication 560's simplified worksheet reduces the effective rate to approximately 20% of net earnings from self-employment, after the deduction for one-half of self-employment tax.
Who is eligible for a Solo 401(k)?
Any self-employed individual or business owner with no common-law employees other than a spouse — sole proprietors, single-member LLCs, partners, and S-corp/C-corp owner-employees with no other staff. If you hire even one common-law employee who works 1,000+ hours a year, you generally must offer them the same plan, which usually means switching to a standard 401(k) or SEP IRA.
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