2024 Solo 401k Limits & Deadlines
- Contribution limit: The solo 401k contribution limit for 2024 is $69,000 ($76,500 if you’ll be at least 50 years of age by December 31, 2024).
- Contribution breakdown: As an employee, you can contribute up to 100% of your income up to $23,000 ($30,500 if age 50+). As an employer, you can contribute up to 25% of your compensation (approximately 20% if you’re not incorporated). Total employee and employer contributions must not exceed $69,000 ($76,500 if age 50+). Employee contributions can be made to a traditional or Roth solo 401k, while employer contributions can only be made with pre-tax income into a traditional solo 401k.
- Plan set up and election deadline: To make employee contributions to your solo 401k, you must formerly file an election that states how much you’re going to contribute as an employee, and to which accounts it should go towards (pre-tax or Roth). Solo 401k plan elections generally must be made by the last day of the calendar year, on December 31, 2024. If you do not have a solo 401k plan yet, but wish to set one up and make employee contributions for 2024, you must establish your plan and make an election by December 31, 2024.
- Contribution deadline: You have until the federal tax filing deadline (March 17, 2025 for S corps, multi-member LLCs, and partnerships, and April 15, 2025 for C corps, sole proprietorships, and LLCs taxed as sole proprietorships) to make your contribution. You can get an additional six months to make your contribution if you file for a tax extension.
2025 Solo 401k Limits & Deadlines
Contribution deadline: You have until the federal tax filing deadline (March 17, 2026 for S corps, multi-member LLCs, and partnerships, and April 15, 2026 for C corps, sole proprietorships, and LLCs taxed as sole proprietorships) to make your contribution. You can get an additional six months to make your contribution if you file for a tax extension.
Contribution limit: The solo 401k contribution limit for 2025 is $70,000 ($77,500 if you’ll be at least 50 years of age by December 31, 2025).
Contribution breakdown: As an employee, you can contribute up to 100% of your income up to $23,500 ($31,000 if age 50+). As an employer, you can contribute up to 25% of your compensation (approximately 20% if you’re not incorporated). Total employee and employer contributions must not exceed $70,000 ($77,500 if age 50+). Employee contributions can be made to a traditional or Roth solo 401k, while employer contributions can only be made with pre-tax income into a traditional solo 401k.
Plan set up and election deadline: To make employee contributions to your solo 401k, you must formerly file an election that states how much you’re going to contribute as an employee, and to which accounts it should go towards (pre-tax or Roth). Solo 401k plan elections generally must be made by the last day of the calendar year, on December 31, 2025. If you do not have a Solo 401k plan yet, but wish to set one up and make employee contributions for 2025, you must establish your plan and make an election by December 31, 2025.
Looking to open a Solo 401k plan? Get started today with just a few clicks – The Carry Solo 401k Plan is a featured-packed self-directed account that lets you invest in both traditional and alternative assets, take out a loan, or do a mega backdoor Roth conversion with a few clicks.
With a Solo 401k, you contribute to your plan as both the employer and the employee. Contribution limits and deadlines are different for both sides, and can vary even further depending on your business entity. If you’re considering opening an account and making contributions, here’s a full breakdown of how much you’re allowed to contribute for 2025, and important deadlines to remember.
2025 solo 401k contribution limits
Solo 401k contribution limit: The total Solo 401k contribution limit is $70,000 in 2025. Solo 401k contribution limits are split between the employee side and the employer side. They each have different limits and rules.
Catch-up contributions: If you’ll be at least 50 years old by December 31, 2025 you’re also given $7,500 in catch-up contributions, bringing your total solo 401k contribution limit to $77,500.
Employee contribution limits: Employees can contribute up to 100% of their income, up to $23,500 ($31,000 if age 50+). Contributions can be made as either pre-tax or Roth.
Employer contribution limits: Because the total contribution limit to a Solo 401k is $70,000, if you max out your employee contributions, you’re left with $46,500 in room remaining to make employer contributions. Employer contributions are calculated by using 25% of your compensation if your business is incorporated, and approximately 20% if your business is unincorporated. Compensation is your net adjusted self-employment earnings or W-2 income.
Also read: Solo 401k Contribution Types Explained
How much can I contribute into my Roth solo 401k for 2025?
In 2025, the Roth Solo 401k contribution limit is $23,500 ($31,000 if age 50+). Because Roth contributions can only be made by employees, the Roth Solo 401k contribution limit is the same as the employee contribution limit. To contribute even more to a Roth Solo 401k than the actual contribution limit, you can do a mega backdoor Roth solo 401k conversion.
Overview of the solo 401k contribution limits for 2025
| Contribution Type | Contribution Amount |
|---|---|
| Employee | $23,500 ($31,000 if for ages 50 or older) |
| Employer | 25% of W-2 earnings or net adjusted self-employment earnings (~20% if you’re not incorporated) |
| TOTAL | $70,000 ($77,500 if for ages 50 or older) |
2024 Solo 401k contribution limits
Solo 401k contribution limit: The total Solo 401k contribution limit is $69,000 in 2024. Solo 401k contribution limits are split between the employee side and the employer side. They each have different limits and rules.
Catch-up contributions: If you’ll be at least 50 years old by December 31, 2024 you’re also given $7,500 in catch-up contributions, bringing your total Solo 401k contribution limit to $76,500.
Employee contribution limits: Employees can contribute up to 100% of their income, up to $23,000 ($30,500 if age 50+). Contributions can be made as either pre-tax or Roth.
Employer contribution limits: Because the total contribution limit to a Solo 401k is $69,000, if you max out your employee contributions, you’re left with $46,000 in room remaining to make employer contributions. Employer contributions are calculated by using 25% of your W-2 earnings or net adjusted self-employment earnings if your business is incorporated, and approximately 20% if your business is unincorporated.
How much can I contribute to my Roth Solo 401k in 2024?
In 2024, the Roth Solo 401k contribution limit is $23,000 ($30,500 if age 50+). Roth contributions can only be made through employee contributions so it is the same limit as the employee limit. You can choose whether you make your contribution with pre-tax income to your pre-tax Solo 401k account, or with after-tax income to your Roth Solo 401k account.
Overview of the Solo 401k contribution limits for 2024
| Contribution Type | Contribution Amount |
|---|---|
| Employee | $23,000 ($30,500 if for ages 50 or older) |
| Employer | 25% of compensation (~20% if you’re not incorporated) |
| TOTAL | $69,000 ($76,500 if for ages 50 or older) |
Solo 401k Contribution Deadlines for 2025
Contribution deadlines can be a little bit tricky since there are a few different dates to remember. Not only do employees and employers have different deadlines, it can also vary depending on your business entity.
A lot of dates are mentioned below. Here’s a quick overview before you dive in to help make sense of everything.
- Because you make contributions as both the employee and the employer with a Solo 401k, the contribution deadlines for each type are different.
- Employees must set up their Solo 401k and file an election by the last day of the year, each year they want to contribute. For 2025, the deadline is December 31, 2025. Filing an election only requires you to officially determine how much you’ll contribute and which accounts they’ll be going to (Roth or pre-tax). Then, you have until the federal tax deadline to actually contribute the funds into your account. This year, the federal tax deadline is April 15, 2026.
- The contribution deadline for employers is also the federal tax deadline, April 15, 2026.
- However, if your business is an S corporation, partnership, or LLC taxed as a corporation, your contribution is one month earlier, March 15, 2026.
Deadlines for employees
Employees have two different deadlines: One for setting up an account and filing a deferral election, and another for actually sending the money and making the contribution into your account.
First deadline: Election deadline – December 31, 2025
If you don’t have a Solo 401k already, you must set up your account and file your deferral election before the end of the year, December 31, 2025. If you miss the deadline, you won’t be able to make contributions for this year. You don’t have to send any money by this date, you only need to file the election. Basically, you’re telling the IRS exactly how much you’re going to contribute that year AND if they’ll be going towards a traditional Solo 401k as pre-tax income or a Roth Solo 401k as after-tax income.
Learn more about Solo 401k elections here.
Second deadline: Funding deadline – April 15, 2026
After you file your deferral election, you have until the federal tax deadline to actually make the contributions into your Solo 401k account, which is April 15, 2026.
| Event | Deadline |
|---|---|
| Open a Solo 401k / file election | December 31, 2025 |
| Contribution deadline for employee contributions | April 15, 2026 |
Deadlines for employers
For employers, the contribution deadline depends on how your business is structured.
- If your business is a sole proprietorship, C corporation, or LLC taxed as a sole proprietorship, your contribution deadline is the federal tax deadline April 15, 2026.
- If your business is an S corporation, partnership, or LLC taxed as a corporation, your contribution deadline is March 15, 2026.
You can also file for an extension
If approved, you’ll get an additional six months to make your contributions.
- A sole proprietorship, C corporation, and LLC taxed as a sole proprietorship will have until October 15, 2026.
- A partnership, S corporation, and LLC taxed as a corporation will have until September 15, 2026.
| Entity Type | Contribution Deadline | Contribution Deadline After Extension |
|---|---|---|
| Sole Proprietorship | April 15, 2026 | October 15, 2026 |
| LLC taxed as a sole proprietorship | April 15, 2026 | October 15, 2026 |
| C corporation | April 15, 2026 | October 15, 2026 |
| Partnership | March 15, 2026 | September 15, 2026 |
| LLC taxed as a corporation | March 15, 2026 | September 15, 2026 |
| S corporation | March 15, 2026 | September 15, 2026 |
I don’t have a Solo 401k plan, but want to set one up for the current tax year. What is the deadline?
If you don’t have a Solo 401k plan, you must establish a plan and file your elections by December 31 of the year you want to make contributions for.
You only need to set up the plan and file an election for the tax year. No money needs to be contributed to the plan until the federal tax filing deadline, the following year.
2024 vs 2025 contribution limits
- The Solo 401k contribution limit is $69,000 in 2024 vs. $70,000 in 2025.
- In 2024, if you’ll be at least 50 years of age by December 31, you can contribute an additional $7,500 in catch-up contributions. This increases the total Solo contribution to $76,500 in 2024. In 2025, catch-up contributions stay at $7,500 increasing the total Solo contribution to $77,500 in 2024
- In 2025, employees can contribute $500 more than they could in 2024.
- When you max out employee contributions, employers were left with $46,000 in contribution room in 2024. In 2025, maxing out employee contributions would leave you with $46,500 in contribution room.
| Contribution Type | 2025 Limits | 2024 Limits |
|---|---|---|
| Employee Elective Deferrals | $23,500 ($31,000 if age 50 or older) | $23,000 ($30,500 if age 50 or older) |
| Employee catch-up contributions | $7,500 | $7,500 |
| Employer contributions | 25% of compensation (20% if you’re not incorporated) | 25% of compensation (20% if you’re not incorporated) |
| Total | $70,000 ($77,500 if age 50+) | $69,000 ($76,500 if age 50+) |
Solo 401k Contribution Limits for Prior Years
Contribution limits for the Solo 401k rise by about $1,000 each year.
- 2023: 66,000
- 2022: 61,000
- 2021: $58,000
- 2020: $57,000
- 2019: $56,000
- 2018: $55,000
- 2017: $54,000
- 2016: $53,000
Do I need to contribute to a Solo 401k every year?
No, there is no minimum contribution requirement with a solo 401k. You do not need to contribute to your solo 401k plan every year and your account will remain open in good standing. It’s entirely your decision how much you contribute, and to which accounts (Roth or pre-tax).
Tax Deduction Limits
While Roth Solo 401k contributions are not tax deductible, traditional pre-tax Solo 401k contributions are deducted from your taxable income. Since both employee and employer contributions can be made towards a pre-tax Solo 401k, your could potentially get a tax deduction up to the Solo 401k contribution limit:
- In 2025, you could get a tax deduction of up to $70,000 if you’re under 50 years old, or $77,500 if you’re 50 years of age or older.
- In 2024, you could get a tax deduction of up to $69,000 if you’re under 50 years old, or $76,500 if you’re 50 years of age or older.
Not all Solo 401k plans come with a Roth option. Compare your different provider options here.
Frequently asked questions
A lot of numbers and dates were mentioned in this guide. Here are some frequently asked questions about the Solo 401k contribution limits and deadlines for 2024 and 2025.
What is the Solo 401k contribution limit for 2025?
The Solo 401k contribution limit for 2025 is $70,000. If you’ll be 50 years of age or older by December 31, 2025, the limit is $77,500 when you account for catch-up contributions of $7,500.
What is the Solo 401k contribution limit for 2024?
The solo 401k contribution limit for 2024 is $60,000. If you’ll be 50 years of age or older by December 31, 2024, the limit is $76,500 when you account for catch-up contributions of $7,500.
Use our solo 401k contribution calculator to determine your contribution room.
How do contributions work for a Solo 401k?
With a Solo 401k, you make contributions as both the employer and the employee. Employees can contribute up to 100% of their compensation up to a maximum of $23,500 for 2025 and $23,000 for 2024. Employers can contribute up to 25% of W-2 earnings or net adjusted self-employment earnings (approximately 20% if you’re unincorporated). The total contributions from both sides must not exceed the total contribution limit of a Solo 401k, which is $70,000 for 2025 and $69,000 for 2024.
Can I pick whether I contribute as pre-tax or Roth?
Yes, you can choose how much you want to put into either account. Note that not all Solo 401k plans come with a Roth option. If offered, only employee contributions have the option to be made as Roth. Employer contributions can only be made into a pre-tax Solo 401k account.
What’s the difference between pre-tax and Roth contributions?
The best Solo 401k plans offer both a pre-tax and Roth account, and they work the same way as a traditional and Roth IRA.
- Contributions to a pre-tax Solo 401k are made with pre-tax income and you get a tax deduction for the amount you contribute. Your money grows tax-deferred until retirement. When you withdraw from the account in retirement, it gets taxed as ordinary income.
- Contributions to a Roth Solo 401k are made with after-tax income and you get no tax deductions when you make the contribution. However, your withdrawals in retirement are tax-free no matter how large your investment profits may be.
What is the Solo 401k contribution deadline?
Not only do employee and employer contributions have different limits, they also have different rules around deadlines.
Employee contributions
- An election must be filed by December 31.
- After filing an election, you have until the federal tax-filing deadline next year (April 15) to actually pay the money into your account.
Employer contributions
- Employers running a sole proprietorship, C corporation, or LLC taxed as a sole proprietorship have until the federal tax filing deadline (April 15).
- Employers running a partnership, S corporation, or LLC taxed as a corporation have until March 15.
- Employers can file for an extension that gives them six additional months to make their contributions after the stated contribution deadlines.
Looking to open a Solo 401k plan? Get started today with just a few clicks – The Carry Solo 401k Plan is a featured-packed self-directed account that lets you invest in both traditional and alternative assets, take out a loan, or do a mega backdoor Roth conversion with a few clicks.
Need clarity on Solo 401k contributions? Learn about employee vs. employer contributions, the right bank account to use, and how to avoid over-contributions.