Use our Solo 401k Contribution Calculator to estimate how much you can contribute to your Solo 401k for the 2024 and 2025 tax years. For a quick overview of contribution types, limits, and rules for a Solo 401k, read the information below before getting started.
Important Disclaimer: This calculator is intended for educational and illustrative purposes only and provides estimates. See the full disclaimer below.
The Solo 401k Handbook
Learn how self-employed professionals can contribute more, reduce taxes,* and invest with greater control– using one of the most powerful retirement plans available. Download the free guide, updated for 2025.
**Solo 401(k) eligibility and contribution limits depend on IRS rules. Tax benefits depend on your individual situation. Not all business owners or side-income earners qualify. 2025 limits ($70,000 or $77,500 with catch-up) depend on income and plan design. Plan administrators—not Carry—are responsible for compliance. Carry does not provide tax advice, consult a tax advisor.
Solo 401k Contribution Calculator
This calculator helps self-employed individuals estimate their maximum Solo 401k contribution limits. Enter your income, business type, and age to see how much you can contribute as both an employee and employer, based on current IRS rules. The calculator also shows your potential tax savings, helping you maximize your retirement contributions.
Solo 401k Contribution Calculator
This calculator helps self-employed individuals determine their maximum Solo 401k contribution limits. Enter your income, business type, and age to see how much you can contribute as both employee and employer, based on current IRS limits. The calculator shows your potential tax savings and helps you maximize your retirement savings.
Solo 401k Contribution Summary
Open A Solo 401k with Carry
Designed specifically for self-employed go-getters, the Carry Solo 401k can help you supercharge your retirement savings, cut your tax bill, and invest with total freedom.
Solo 401k Contribution Rules & Guidelines
Employee Contribution Rules
As a self-employed individual, you can make employee deferrals up to the annual limit ($23,000 for 2024 and $23,500 for 2025). For 2024, if you're 50 or older, you can make an additional catch-up contribution of $7,500. For 2025, catch-up contributions vary by age:
- Ages 50-59: $7,500 additional catch-up
- Ages 60-63: $11,250 additional catch-up
- Ages 64+: $7,500 additional catch-up
Timing: Employee contributions must be made by December 31 of the tax year. For example, 2024 employee contributions must be completed by December 31, 2024.
Employer Contribution Rules
As the employer, you can also make profit-sharing contributions:
- Sole Proprietors/Single-Member LLCs: Up to 20% of your net self-employment income (net profit minus half of self-employment tax)
- Corporations: Up to 25% of W-2 compensation
Employer contributions are always pre-tax (Traditional) and cannot be made as Roth contributions.
Timing: Employer contributions can be made until your tax filing deadline, including extensions. This means you can potentially make employer contributions for 2024 as late as October 15, 2025, if you file an extension.
Total Contribution Limits
The combined employee and employer contributions cannot exceed the annual limit ($69,000 for 2024 and $69,500 for 2025).
With catch-up contributions, the total limits are:
- 2024: $76,500 (for age 50+)
- 2025:
- Ages 50-59: $77,000
- Ages 60-63: $80,750
- Ages 64+: $77,000
Contribution Process
The process for making contributions varies based on your business structure:
- Sole Proprietors/Single-Member LLCs: Both employee and employer contributions are made directly to your Solo 401k provider. You'll need to specify which portion is employee deferral and which is employer contribution.
- S-Corporations: Employee deferrals must be made through formal payroll deductions from your W-2 wages. Employer contributions are made directly from the business to the Solo 401k plan as a business expense. Proper documentation is essential to distinguish between your salary and distributions.
- C-Corporations: Employee deferrals are typically made through payroll deductions throughout the year. Employer contributions are made directly from the business to the Solo 401k plan.
Most Solo 401k providers have specific forms to document your contributions properly for tax reporting purposes. S-Corporation owners should maintain detailed records of payroll deductions for employee contributions to support their tax filings.
Important Considerations
- If you have multiple employers or participate in another employer's 401k plan, the employee deferral limit applies across all plans combined
- Employer contributions are not affected by participation in other plans
- Contributions must be made by the tax filing deadline (including extensions)
- For sole proprietors, your contribution limit is based on your net earnings from self-employment
- For S-Corporation owners, only your W-2 wages (not distributions) count for employee deferrals
- S-Corporation owners must establish "reasonable compensation" for their W-2 wages to avoid IRS scrutiny. Talk to your accountant.
- S-Corporation employer contributions are limited to 25% of W-2 compensation, not including distributions
- If your business has a net loss for the year, you cannot make employer contributions
- You must establish your Solo 401k plan by December 31 of the tax year to make contributions for that year
Tax Advantages
Traditional contributions reduce your current taxable income, while Roth contributions allow for tax-free growth and withdrawals in retirement. Consider your current and expected future tax rates when deciding between Traditional and Roth contributions.
Sole Proprietor/Single-Member LLC Special Considerations
Sole Proprietors and Single-Member LLC owners face specific considerations when making Solo 401k contributions:
- Self-Employment Tax: Your contribution calculations are based on net earnings after deducting half of your self-employment tax.
- Contribution Basis: Your employee and employer contributions are calculated from the same income source (Schedule C net profit).
- Simplified Administration: No formal payroll system is required, making contribution processing more straightforward.
- Documentation: Keep detailed records of your business income and how contribution amounts were calculated.
- Tax Reporting: Employee contributions are reported on your personal tax return, while employer contributions are reported as a business expense on Schedule C.
S-Corporation Special Considerations
S-Corporation owners face unique considerations when making Solo 401k contributions:
- Reasonable Compensation: The IRS requires S-Corporation owners to pay themselves "reasonable compensation" as W-2 wages before taking distributions. This compensation must be comparable to what would be paid for similar services in your industry.
- Contribution Basis: Employee deferrals can only be made from W-2 wages, not from distributions or pass-through profits.
- Tax Advantages: S-Corporation owners can potentially reduce self-employment taxes by taking a portion of their income as distributions, but this strategy must be balanced with maintaining sufficient W-2 wages for retirement contributions.
- Documentation: Maintain clear documentation of your compensation structure and the business rationale for your salary level to support your position in case of an IRS audit.
- Payroll Requirements: Employee contributions must be made through formal payroll deductions, requiring proper payroll processing.
C-Corporation Special Considerations
C-Corporation owners should be aware of these specific considerations for Solo 401k contributions:
- Corporate Structure: As a C-Corporation owner-employee, your contributions are based solely on your W-2 wages from the corporation.
- Double Taxation: While C-Corporations face potential double taxation on profits, retirement contributions can help reduce corporate taxable income.
- Compensation Planning: Carefully structure your salary to optimize retirement contributions while managing corporate tax liability.
- Payroll Integration: Employee contributions must be processed through your corporate payroll system.
- Corporate Deduction: Employer contributions are deductible business expenses for the corporation, potentially reducing corporate tax liability.
Important Disclaimer
This calculator provides estimates only and should be used for educational purposes only.
- Tax laws and regulations are complex and subject to change
- Individual circumstances may vary significantly
- The calculator provides estimates based on current IRS rules
- Actual contribution limits may differ based on your specific situation
- For S-Corporation owners, this calculator assumes your W-2 wages constitute "reasonable compensation" as required by the IRS
- The calculator does not evaluate whether your S-Corporation compensation structure would withstand IRS scrutiny
- S-Corporation owners should consult with a tax professional to determine appropriate wage levels
- This calculator does not account for state-specific tax implications
- The calculator does not consider potential impacts of the net investment income tax
- Results may be affected by other retirement plans you participate in
- This calculator does not provide tax, legal, or financial advice
- Consult with a qualified tax professional or financial advisor before making contribution decisions
- By using this calculator, you acknowledge that you understand these limitations and will seek professional advice for your specific situation
By using this calculator (version 1.0.35H), you acknowledge that you understand these limitations and will seek professional advice for your specific situation.
Solo 401k Contribution Rules & Guidelines
Employee Contribution Rules
As a self-employed individual, you can make employee deferrals up to the annual IRS limit ($23,000 for 2024 and $23,500 for 2025). If you’re age 50 or older in 2024, you’re eligible for an additional catch-up contribution of $7,500. For 2025, catch-up contributions vary by age:
- Ages 50-59: $7,500 additional catch-up
- Ages 60-63: $11,250 additional catch-up
- Ages 64+: $7,500 additional catch-up
You may choose to make contributions as either Traditional (pre-tax) or Roth (after-tax).
Timing: Employee contributions must generally be elected by December 31 of the tax year. However, owner-employees may deposit contributions as late as their personal tax-return deadline, including extensions.
Employer Contribution Rules
As the employer, you can also make profit-sharing contributions:
✅ Sole Proprietors/Single-Member LLCs: Up to 20 percent of your net self-employment income (net profit minus half of self-employment tax)
✅ Corporations: Up to 25 percent of W-2 compensation
Employer contributions must be Traditional (pre-tax). Roth contributions are not allowed for the employer portion.
Timing: Employer contributions can be made until your tax filing deadline, including extensions. For 2024, this could be as late as October 15, 2025, if you file an extension.
Total Contribution Limits
The combined employee and employer contributions are capped at:
- 2024: $69,000
- 2025: $70,000
With catch-up contributions included:
- 2024: $76,500 (for age 50+)
- 2025:
- Ages 50-59: $77,500 (base $70,000 + $7,500 catch-up)
- Ages 60-63: $81,250 (base $70,000 + $11,250 higher catch-up)
- Ages 64+: $77,500 (base $70,000 + $7,500 catch-up)
Contribution Process
The process for making contributions varies depending on your business structure:
- Sole Proprietors/Single-Member LLCs: Both employee and employer contributions are made directly to your Solo 401k provider. You’ll need to specify which portion is employee deferral and which is employer contribution.
- S-Corporations: Employee deferrals must be made through formal payroll deductions from your W-2 wages. Employer contributions are made directly from the business to the Solo 401k plan and treated as a business expense. Proper documentation is essential to distinguish between your salary and distributions.
- C-Corporations: Employee deferrals are typically made through payroll deductions throughout the year. Employer contributions are made directly from the business to the Solo 401k plan.
Most Solo 401k providers have specific forms to document your contributions correctly for tax reporting purposes. S-Corporation owners should maintain detailed payroll records to support their tax filings.
Important Considerations
- If you have multiple employers or participate in another employer’s 401k plan, the employee deferral limit applies across all 401k plans combined.
- Employer contributions are not affected by participation in other plans.
- Contributions must be made by the tax filing deadline (including extensions)
- Sole proprietor contribution limits are based on net earnings.
- S-Corp owners must pay themselves reasonable compensation to avoid IRS scrutiny.
- S-Corp employer contributions are limited to 25 percent of W-2 wages, not total business income.
- If your business has a net loss for the year, you cannot make employer contributions.
- Plan establishment deadline (SECURE 2.0 update):
- A sole proprietor with no employees may now adopt a Solo 401k up to their personal tax-return deadline (without extensions) and still make contributions for the prior year.
- However, to make employee contributions, the plan must still be established by December 31 of that tax year.
Tax Advantages
Traditional contributions may reduce your current taxable income, while Roth contributions grow tax-free and may be withdrawn tax-free in retirement. Consider your current vs. expected future tax rate when choosing between Traditional and Roth options.
Special Considerations by Business Type
Sole Proprietor/Single-Member LLC
- Self-Employment Tax: Your contribution calculations are based on net earnings after deducting half of your self-employment tax.
- Contribution Basis: Your employee and employer contributions are calculated from the same income source (Schedule C net profit).
- Simplified Administration: No formal payroll system is required, making contribution processing more straightforward.
- Documentation: Keep detailed records of your business income and how contribution amounts were calculated.
- Tax Reporting: Employee contributions are reported on your personal tax return, while employer contributions are reported as a business expense on Schedule C.
S-Corporation
- Reasonable Compensation: The IRS requires S-Corporation owners to pay themselves “reasonable compensation” as W-2 wages before taking distributions. This amount should reflect what would typically be paid for similar services in your industry.
- Contribution Basis: Employee deferrals can only be made from W-2 wages, not from distributions or pass-through profits.
- Tax Advantages: S-Corporation owners can potentially reduce self-employment taxes by taking a portion of their income as distributions, but this strategy must be balanced with maintaining sufficient W-2 wages for retirement contributions.
- Documentation: Maintain clear documentation of your compensation structure and the business rationale for your salary level to support your position in case of an IRS audit.
- Payroll Requirements: Employee contributions must be made through formal payroll deductions, requiring proper payroll processing.
C-Corporation Special Considerations
- Corporate Structure: As a C-Corporation owner-employee, your contributions are based solely on your W-2 wages from the corporation.
- Double Taxation: While C-Corporations face potential double taxation on profits, retirement contributions can help reduce corporate taxable income.
- Compensation Planning: Carefully structure your salary to optimize retirement contributions while managing corporate tax liability.
- Payroll Integration: Employee contributions must be processed through your corporate payroll system.
- Corporate Deduction: Employer contributions are deductible business expenses for the corporation, potentially reducing corporate tax liability.
Important Disclaimer
This calculator is intended for educational purposes and provides estimates only.
- Tax laws and regulations are complex and subject to change
- Individual circumstances may vary significantly
- The calculator provides estimates based on current IRS rules
- Actual contribution limits may differ based on your specific situation
- For S-Corporation owners, this calculator assumes your W-2 wages constitute “reasonable compensation” as required by the IRS.
- The calculator does not evaluate whether your S-Corporation compensation structure would withstand IRS scrutiny.
- S-Corporation owners should consult with a tax professional to determine appropriate wage levels.
- This calculator does not account for state-specific tax implications.
- The calculator does not consider potential impacts of the net investment income tax.
- Results may be affected by other retirement plans you participate in.
- This calculator does not provide tax, legal, or financial advice.
- Consult with a qualified tax professional or financial advisor before making contribution decisions.
- By using this calculator, you acknowledge that you understand these limitations and will seek professional advice for your specific situation.
By using this calculator (version 1.0.35H), you acknowledge that you understand these limitations and agree to seek professional advice for your specific situation.
How to Use the Solo 401k Contribution Calculator
Step 1: Date of birth
This step determines whether you’re eligible for catch-up contributions.
Step 2: Business structure
Select whether your business operates as an LLC, S-Corp, C-Corp, partnership, or sole proprietorship. All business structures are eligible for a Solo 401k, but certain contribution rules can vary depending on your business entity.
Step 3: Tax year
Choose whether you’re calculating contributions for the 2024 or 2025 tax year.
Step 4: Income and expenses
Enter your gross annual income from your business, and your estimated total expenses.
Step 5: Contribution type
Choose whether you’re contributing to your Traditional pre-tax account, Roth post-tax account, or both.
Solo 401k Contributions Explained
Contribution limits
2024
- $69,000 if under 50 years of age
- $76,500 if age 50+
2025
- $70,000 if under 50 years of age
- $77,500 if age 50+
- $81,250 if age 60-63
Learn more about Solo 401k contribution limits.
Contribution Calculations
📌 For 2024:
Out of the 2024 Solo 401k contribution limit of $69,000, here’s how the contributions get broken down by employee and employer contributions.
- Employees can contribute up to 100 percent of their income up to a maximum of $23,000.
- Employers can contribute up to 25 percent of their compensation if their business is incorporated, and up to approximately 20 percent if their business is not incorporated.
📌 For 2025:
Out of the 2025 Solo 401k contribution limit of $70,000, here’s how the contributions get broken down by employee and employer contributions.
- Employees can contribute up to 100 percent of their income up to a maximum of $23,500 (or $31,000 if for ages 50 or older).
- Employers can contribute up to 25 percent of their compensation if their business is incorporated, and up to approximately 20 percent if their business is not incorporated.
What Income Can Be Contributed?
Eligible compensation includes your W-2 wages or your net adjusted self-employment earnings:
For self-employed individuals, compensation is your earned income, which is your net earnings from self-employment after deducting:
- Half of your self-employment tax, and
- Contributions to yourself.
📝 Note: You’ll usually have to pay self-employment taxes if you had net earnings of $400 or more from self-employment. The amount of income subject to self-employment tax is generally 92.35 percent of your net earnings from self-employment. Learn more here.
📌 As for what type of earned income is allowed to be contributed to a Solo 401k plan, you can read: What Income Is Eligible To Be Contributed To A Solo 401k?
Contribution Types
Since you’re the owner of your own business, you can contribute to your Solo 401k as both the employee and employer. Employees can contribute as both pre-tax or post-tax, while employers can only contribute as pre-tax.
- Pre-Tax Contributions (Traditional): Contributions to your pre-tax Solo 401k account are made with pre-tax income and are tax deductible. When you take withdrawals from your pre-tax account in retirement, it gets taxed as regular income.
- Post-Tax Contributions (Roth): Contributions to your post-tax Solo 401k account (also known as your Roth Solo 401k) are made with post-tax income. You get no tax breaks for your contribution, but withdrawals in retirement are tax-free.
Frequently Asked Questions
What is the maximum I can contribute to my Solo 401k?
For 2024, you can contribute up to a maximum of $69,000. If you’re at least 50 years of age, you also get catch up contributions in the amount of $7,500 bringing your total contribution limit to $76,500.
For 2025, you can contribute up to a maximum of $70,000. If you’re:
- Age 50–59 or 64+: Add a $7,500 catch-up contribution for a total of $77,500
- Age 60–63: Add an $11,250 catch-up contribution for a total of $81,250
How much can I contribute to a Roth Solo 401k?
Only employee contributions can be made into the Roth post-tax Solo 401k account. For 2024 you may defer up to $23,000 (plus $7,500 catch-up if age 50+).
For 2025 the elective-deferral cap is $23,500, with catch-up based on age:
- Ages 50–59 or 64+: $7,500
- Ages 60–63: $11,250
The calculator will apply these limits when you choose the “Roth” option.
What is the Mega Backdoor Roth?
If you wish, you can perform a Mega Backdoor Roth Solo 401k, which allows you to contribute the entire Solo 401k limit as Roth post-tax. Essentially, you would be able to contribute:
- For 2024: up to $69,000 total (or $76,500 with the regular $7,500 catch-up).
- For 2025: up to $70,000 total, plus the applicable catch-up (so $77,500 or $81,250 depending on age-band).
📝 Note: Not every Solo 401k document permits after-tax employee contributions. Verify that your provider allows them.
Are Solo 401k contributions tax deductible?
Yes, contributions made to your pre-tax Solo 401k account are tax deductible and get deducted from your taxable income for the year. However, withdrawals in retirement get taxed as regular income. On the other hand, contributions made to your post-tax account do not give you any tax deductions, but give you tax-free withdrawals in retirement.
I also have a 401k from my day job. Will my Solo 401k contribution limits be affected?
Yes. Employee contributions are aggregated across all of your 401k plans. If you contributed money to your 401k at work, you’ll have to deduct that from your employee contribution room for the year.
✏️ Hypothetical Example: If you’re under 50 years of age, employees can contribute up to $23,000 for 2024. If you contributed $5,000 into your 401k at work, you can contribute $18,000 more to your Solo 401k as an employee.
How much can I rollover into my Solo 401k?
There are no limits on how much you can rollover into your Solo 401k from other retirement accounts you own. You can rollover assets from any retirement plan into your Solo 401k, except from a Roth IRA.
📌 Further Readings:
Disclaimer:
The Carry Learning Center is operated by The Vibes Company Inc. (“Vibes”) and contains generalized educational content about personal finance topics. While Vibes provides educational content and technology services, all investment advisory services discussed on this website are provided exclusively through its wholly-owned subsidiary, Carry Advisors LLC (“Carry Advisors”), an SEC registered investment adviser. The information contained on the Carry Learning Center should not be construed as personalized investment advice and should not be considered as a solicitation to buy or sell any security or engage in a particular investment, accounting, tax or legal strategy. Vibes is not providing tax, legal, accounting, or investment advice. You should consult with qualified tax, legal, accounting, and investment professionals regarding your specific situation.
The accounts, strategies and/or investments discussed in this material may not be suitable for all investors. All investments involve the risk of loss, and past performance does not guarantee future results. Investment growth or profit is never a guarantee. All statements and opinions included on the Carry Learning Center are intended to be current as of the date of publication but are subject to change without notice.
To access investment advisory services through Carry Advisors, you must be a client of Vibes on an eligible membership plan. For more information about Carry Advisors’ investment advisory services, please see our Form [ADV Part 2A] (https://files.adviserinfo.sec.gov/IAPD/Content/Common/crd_iapd_Brochure.aspx?BRCHR_VRSN_ID=916200) brochure and [Form CRS] (https://reports.adviserinfo.sec.gov/crs/crs_323620.pdf) or through the SEC’s website at [www.adviserinfo.sec.gov] (http://www.adviserinfo.sec.gov/).