Solo 401(k) Calculator

Calculate your maximum allowed Solo 401(k) contribution for 2026 as a self-employed individual or small business owner. This tool determines your contribution limit as both an "employee" and an "employer," factoring in your business income, business structure (Sole Proprietor or S-Corp), and age. See how these contributions can grow your retirement savings over time.

This calculator is designed for freelancers, independent contractors, and business owners with no employees other than a spouse. If you are exploring other self-employed retirement options, compare your results with our SEP IRA contribution calculator or see how this fits into your overall plan with the main retirement calculator.

The calculator provides a complete breakdown of your potential contributions: your employee salary deferral, your employer profit-sharing contribution, and any eligible catch-up contributions. You'll also see a projection of your Solo 401(k) balance at retirement, a contribution utilization score, and charts visualizing your annual contribution breakdown and long-term growth.

Begin by entering your financial and personal details into the calculator. Start with the Self-Employment Income section. Input your Net Self-Employment Income, which is your business revenue minus your expenses. Then, select your Business Type. Enter 1 if you operate as a Sole Proprietor or a single-member LLC taxed as a sole proprietorship. Enter 0 if your business is an S-Corporation and you receive a W-2 salary. This distinction is critical as it changes how the employer contribution is calculated.

Next, move to the Personal Details section. Provide your Current Age and your target Retirement Age. These inputs determine your savings timeline and eligibility for catch-up contributions. Enter your Current 401(k) Balance to serve as the starting point for the growth projection. Finally, set an Expected Annual Return to estimate how your investments might perform over time.

For more detailed planning, open the Advanced Settings. Here, you can specify if you are Catch-Up Eligible. Enter 1 for 'Yes' if you are age 50 or older, which allows for an additional contribution. You can also specify a Roth Portion as a percentage. This applies to your employee deferrals, allowing a portion of your contributions to grow tax-free, similar to a Roth IRA. Note that employer contributions must be made on a pre-tax basis.

Once all your information is entered, click "Calculate" to see your results. The tool will display your maximum contribution limits, a projected future balance, and detailed charts breaking down your savings potential.

Net Self-Employment Income

This is the foundation of your contribution calculation. For a sole proprietor, it's your gross income less business expenses (the number on Schedule C of your tax return). For an S-Corp owner, this should be your W-2 salary from the business. The calculator uses this figure to determine the maximum you can contribute as both an "employee" and an "employer."

Business Type (Sole Proprietor vs. S-Corp)

Your business structure directly impacts the "employer" portion of your contribution.

• Sole Proprietor / LLC: The employer contribution is calculated as 20% of your net adjusted self-employment income. The calculator automatically handles the adjustment for self-employment taxes.
• S-Corporation: The employer contribution can be up to 25% of your W-2 compensation.

Choosing the correct type ensures an accurate calculation of your maximum profit-sharing contribution.

Current Age & Retirement Age

Your current age determines if you are eligible for catch-up contributions. If you are 50 or older, you can contribute an additional amount above the standard employee limit. Your retirement age sets the timeframe for the growth projection, showing you how many years your contributions have to compound. Use our retirement age calculator to see how this timeline affects your overall goals.

Current 401(k) Balance

This is the total amount you currently have saved in your Solo 401(k) or other retirement accounts you plan to roll into it. It serves as the starting principal for the long-term growth projection. A higher starting balance can significantly impact your final projected amount due to the power of compounding.

Expected Annual Return

This is the average annual rate of return you expect your investments to generate. A common long-term estimate for a diversified stock portfolio is between 6% and 8%, but you should choose a number that reflects your specific investment strategy and risk tolerance. Remember that this is an estimate; actual returns will vary. To understand the impact of inflation on your returns, read how inflation affects retirement savings.

Catch-Up Eligible (Age 50+)

Federal law allows individuals aged 50 and over to make additional "catch-up" contributions to their retirement plans. For 2026, the 401(k) catch-up amount is $7,500. Under the SECURE 2.0 Act, those aged 60-63 can make a "super catch-up" contribution of $11,250 (instead of $7,500), bringing their total employee contribution to $34,750. Enabling this option adds the applicable catch-up amount to your employee contribution limit, increasing your total potential savings.

Roth Portion

A Solo 401(k) plan can include a Roth option. This input allows you to designate a percentage of your employee contributions to be made on a post-tax basis. Roth contributions do not provide an upfront tax deduction, but qualified withdrawals in retirement are tax-free. This can be a powerful tool for tax diversification. Employer profit-sharing contributions are always pre-tax. Compare this with a Roth vs. Traditional IRA.

This calculator determines your maximum Solo 401(k) contribution by calculating two separate components and then combining them, subject to overall IRS limits.

1. Employee Contribution (Salary Deferral): As the "employee," you can contribute 100% of your compensation up to the annual limit. For 2026, this limit is $23,500. If you are 50 or older and enable the catch-up option, this limit increases by $7,500 to $31,000. The calculator determines this amount first.

2. Employer Contribution (Profit Sharing): As the "employer," your business can make an additional profit-sharing contribution. The calculation depends on your business type:

   • For a Sole Proprietor, it's up to 20% of your net adjusted self-employment income. The calculator first finds your net self-employment income, subtracts one-half of your self-employment taxes, and then applies the 20% rate.
   • For an S-Corporation, it's up to 25% of your W-2 salary.

3. Overall Limit: The total combined contributions from both the employee and employer cannot exceed the overall IRS limit for the year. For 2026, this limit is $70,000 (or $77,500 if making catch-up contributions). The calculator caps your total contribution at this amount.

Finally, the calculator projects the future growth of your account. It starts with your current balance and then simulates year-by-year growth until your specified retirement age. Each year, it adds your total annual contribution and then applies your expected rate of return to the new balance.

The calculations are performed in a specific order to adhere to IRS rules. The formulas below use plain English to explain the logic.

Adjusted Income for Sole Proprietors

For Sole Proprietors, income must be adjusted for self-employment (SE) taxes before calculating the employer contribution.

se_tax_deduction = net_self_employment_income * 0.9235 * 0.5 * 0.153
adjusted_income_for_employer_calc = net_self_employment_income * 0.9235 - se_tax_deduction

For S-Corp owners, the basis for the employer contribution is simply the W-2 salary.

Employee & Catch-Up Contribution

This is the "employee" part of your contribution.

employee_deferral = min(employee_limit_2026, net_self_employment_income)
catch_up_amount = if age >= 50, then catch_up_limit_2026 else 0

Employer Contribution

This is the "employer" profit-sharing part.

# For a Sole Proprietor
employer_contribution_sole_prop = adjusted_income_for_employer_calc * 0.20

# For an S-Corp
employer_contribution_s_corp = w2_salary * 0.25

employer_contribution = min(calculated_employer_contribution, overall_limit - employee_deferral)

Total Contribution

This combines all parts, ensuring the total does not exceed the overall IRS limit.

total_contribution = employee_deferral + employer_contribution + catch_up_amount
max_possible = if age >= 50, then total_limit_catchup_2026 else total_limit_2026
final_total_contribution = min(total_contribution, max_possible)

Growth Projection

The future balance is calculated year by year.

# For each year until retirement:
investment_growth = current_balance * expected_return
ending_balance = current_balance + total_annual_contribution + investment_growth

A common question for self-employed individuals is whether a Solo 401(k) or a SEP IRA is better. Both are excellent retirement plans, but they have key differences.

The Solo 401(k)'s main advantage is its two-part contribution structure. The employee deferral of $23,500 (plus $7,500 catch-up) is made in addition to the employer profit-sharing contribution. For a SEP IRA, the contribution is limited to only the employer portion (up to 25% of compensation for an S-Corp, or 20% of adjusted net income for a sole prop).

This means a Solo 401(k) often allows for higher total contributions, especially at lower to moderate income levels. For example, someone with $50,000 in net income could contribute much more to a Solo 401(k) than a SEP IRA. Use the SEP IRA contribution calculator to run a direct comparison.

The power of the Solo 401(k) comes from the fact that you act in two capacities: as the employee and the employer.

1. The Employee Contribution: This is your salary deferral. As the employee of your own business, you can choose to "defer" up to 100% of your compensation into the plan, up to the annual limit of $23,500 for 2026. This portion can be made as either pre-tax or Roth contributions if your plan allows. This is the part that is most similar to a traditional 401(k) contribution at a large company.

2. The Employer Contribution: This is a profit-sharing contribution. As the employer, your business can contribute a percentage of your compensation to the plan on your behalf. This contribution is always pre-tax and tax-deductible for the business. The percentage is up to 20% for sole proprietors (of adjusted income) and up to 25% for S-Corps (of W-2 salary).

By combining these two roles, you can often save significantly more than in other self-employed plans.

Staying up-to-date on IRS limits is essential for maximizing your savings. Here are the key numbers for the 2026 tax year:

• Employee Elective Deferral: $23,500
• Catch-Up Contribution (Age 50+): $7,500
• SECURE 2.0 "Super" Catch-Up (Ages 60-63): $11,250 (replaces the standard $7,500 catch-up)
• Total Employee Contribution (Age 50+): $31,000
• Total Employee Contribution (Ages 60-63): $34,750
• Total Combined Limit (Employee + Employer): $70,000
• Total Combined Limit with Standard Catch-Up: $77,500
• Total Combined Limit with Super Catch-Up (Ages 60-63): $81,250

These limits are powerful, allowing a self-employed person to potentially save much more than a traditional employee whose employer offers a standard 401(k).

The calculator provides several key metrics to help you understand your retirement savings potential.

• Contribution Utilization Score: This score, from 1 to 99, shows what percentage of your maximum possible contribution you are making. A high score means you are effectively maximizing the tax advantages of your Solo 401(k).
• Employee Deferral: This is the amount you can contribute as the "employee," up to the $23,500 limit (or $31,000 with catch-up) in 2026.
• Employer Contribution: This is the additional profit-sharing amount your business can contribute on your behalf.
• Total Annual Contribution: The sum of your employee, employer, and catch-up contributions. This is the total amount you can add to your plan each year.
• Projected Balance: This is an estimate of your Solo 401(k)'s value at your chosen retirement age, based on your inputs. This helps visualize the long-term impact of your savings strategy.
• Contribution Breakdown Chart: The donut chart visually separates your total contribution into its components: employee deferral, employer profit sharing, and catch-up.
• Growth Projection Chart: The area chart maps out the projected growth of your balance year by year, showing how consistent contributions and compound interest build wealth over time.

If you want to contribute more or accelerate your savings, consider these strategies:

• Maximize Your Employee Deferral: Always aim to contribute the full employee amount ($23,500, or $31,000 if 50+) if your income allows. This is the most direct way to boost your savings.
• Increase Business Income: Since your employer contribution is based on a percentage of your income, growing your business's net profit will directly increase your contribution limit.
• Review Your Business Structure: In some cases, structuring your business as an S-Corp could allow for a higher employer contribution (25% of W-2 salary vs. 20% of adjusted net income for a sole prop). Consult a tax professional to see if this makes sense for you.
• Utilize the Roth Option: If you expect to be in a higher tax bracket in retirement, making Roth contributions can be a smart move. You pay taxes now, but your withdrawals will be tax-free. You can even perform a Roth conversion on existing pre-tax balances.
• Ensure You Use Catch-Up Contributions: If you are age 50 or older, do not forget to take advantage of the additional $7,500 catch-up contribution.

Avoid these common pitfalls when managing your Solo 401(k) plan:

1. Missing the Setup Deadline: You must establish the Solo 401(k) plan by December 31 of the tax year you want to make contributions for.
2. Contributing More Than Your Income: Your total contributions cannot exceed your net self-employment income for the year.
3. Forgetting Form 5500-EZ: If your plan's total assets reach $250,000 or more at the end of the year, you must file Form 5500-EZ with the IRS.
4. Miscalculating the Employer Contribution: The employer contribution formula is complex, especially for sole proprietors. Using a reliable calculator is key to avoiding over-contribution penalties.
5. Ignoring the Plan When Hiring Employees: A Solo 401(k) is only for the business owner and their spouse. If you hire other full-time employees, you will need to terminate the Solo 401(k) and switch to a different plan, like a standard 401(k) or SEP IRA.