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.
Thinking about setting up a Solo 401k for the 2024 tax year? Or do you already have one and need to meet all the deadlines? Either way, staying on top of key dates can help you maximize contributions and avoid potential penalties.
Below, you’ll find every important deadline for setting up your plan, making contributions, and filing IRS forms.
📝 Important: Filing dates may be subject to change, be sure to check the IRS website to confirm the latest information before filing. As always, working with a tax pro can be helpful in ensuring proper filings.
📌 Bonus: Download a printable PDF guide with all the key dates for the 2024 tax year so you always have them handy!
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Solo 401k Important Deadlines
Download a PDF with all the important dates and deadlines you need to know for Solo 401k Plans.
| What’s Due? | Deadline |
|---|---|
| Solo 401k Plan Setup | December 31, 2024 |
| Employee Contribution Election | December 31, 2024 |
| Form 945 | January 31, 2025 (Feb 10 if taxes paid in full) |
| Form 1099-R (Paper Filing) | February 28, 2025 |
| Form 1099-R (E-filing) | March 1, 2025 |
| Contribution Deadline (S Corps, Partnerships, LLCs taxed as S Corps/Partnerships) | March 15, 2025 (Sept 16 if extended) |
| Contribution Deadline (C Corps, Sole Proprietorships, LLCs taxed as Sole Proprietorships) | April 15, 2025 (Oct 15 if extended) |
| Form 8606 | April 15, 2025 |
| Form 5500-EZ | July 31, 2025 (If using calendar year) |
| Extended Contribution Deadline | Sept 16, 2025 (S Corps, Partnerships, LLCs taxed as S Corps/Partnerships) Oct 15, 2025 (C Corps, Sole Proprietorships, LLCs taxed as Sole Proprietorships) |
📌 December 31, 2024
Deadline to Set Up a Solo 401k Plan
(If you don’t already have one)
If you don’t have a Solo 401k plan, are eligible and want to contribute for the 2024 tax year, you must establish a plan by December 31, 2024. To understand eligibility, read our article about Solo 401ks.
Deadline to Make an Election
(If you wish to make employee contributions for the 2024 tax year)
To contribute employee salary deferrals to your Solo 401k, you need to make an election by December 31, 2024. A Solo 401k election is a formal written declaration stating:
- How much you plan to contribute as an employee
- Whether it goes into a pre-tax or Roth account
Since you’re both the employer and employee, this is essentially a signed and dated note to yourself for your records just in case the IRS requests it. You don’t need to deposit money into your Solo 401k yet, but you must have the election documented.
Exception for Sole Proprietors
If you run your business as a sole proprietorship, the SECURE 2.0 Act gives you more time to set up a Solo 401k and make your first elective deferrals. Instead of meeting the December 31, 2024 deadline, you have until your federal tax filing deadline (April 15, 2025).
📝 Important: Extensions do NOT apply — you must finalize your Solo 401k by April 15, 2025.
📌 January 31, 2025
Deadline to File Form 945
(If you took an early distribution from your Solo 401k in 2024)
If you withdrew money early from your Solo 401k plan in 2024 and withheld federal income tax, you must file Form 945 by this date.
Early distributions from a Solo 401k are generally subject to a 10% early withdrawal penalty plus income taxes. Additionally, 20% federal tax withholding is required on eligible rollover distributions.
📝 Exception: If you deposited all required tax payments for 2024 on time, the extended deadline to file Form 945 is February 10, 2025.
📌 February 28, 2025
Deadline to File Form 1099-R (Paper Filing)
(If you moved money out of your Solo 401k in 2024)
If you moved money out of your Solo 401k plan in 2024, you must file Form 1099-R. The deadline for paper filing is February 28, 2025. This generally applies to all withdrawals, rollovers, Roth conversions, Mega Backdoor Roth conversions, RMDs, and Solo 401k loan that went into default and were treated as taxable distributions.
📌 March 1, 2025
Deadline to File Form 1099-R (E-filing)
(Applies if you moved money out of your Solo 401k in 2024)
For those opting for electronic filing, Form 1099-R must be submitted on March 1, 2025. This applies to all withdrawals, rollovers, Roth conversions, Mega Backdoor Roth conversions, RMDs, and failed Solo 401k loan payments.
📌 March 15, 2025
Deadline for Employer & Employee Contributions
(For S corporations, partnerships, and LLCs taxed as S corporations or partnerships)
If your business operates as an S corporation, partnership, or multi-member LLC taxed as an S corp or partnership, you must deposit employer contributions to your Solo 401k by March 15, 2025.
If you previously elected to make employee contributions, those funds must also be deposited by this date.
📝 If you file a tax extension, the deadline extends to September 16, 2025.
📌 April 15, 2025
Deadline for Employer & Employee Contributions
(For C corporations, sole proprietorships, and LLCs taxed as sole proprietorships)
If your business is a C corporation, sole proprietorship, or LLC taxed as a sole proprietorship, you must make employer contributions to your Solo 401k by April 15, 2025.
If you previously elected to make employee contributions, those funds must also be deposited by this date.
📝 If you need more time, filing a tax extension grants you until October 15, 2025 to make these contributions.
Deadline to File Form 8606
(If you contributed to a non-deductible IRA in 2024)
If you contributed to a non-deductible IRA in 2024, you must file Form 8606 to the IRS. This form reports after-tax contributions to an IRA, often part of a Mega Backdoor Roth conversion into a Roth Solo 401k.
You should submit Form 8606 along with your annual tax return by the April 15, 2025 federal tax deadline.
📌 July 31, 2025
Deadline to File Form 5500-EZ
(If you’re closing your Solo 401k or if your account asset value is $250,000 or more)
The deadline to file IRS Form 5500-EZ is seven months after the end of your fiscal year. If your business follows the calendar year, the due date is July 31, 2025.
File Form 5500-EZ if you wish to close your Solo 401k plan, or if your account asset value is $250,000 or more as of December 31, 2024.
📝 Pro Tip: While not required, we generally suggest filing Form 5500-EZ every year, even if you’re not required to. There are edge cases where having a record on file can serve as a safeguard.
📌 September 16, 2025
Extended Contribution Deadline
(For S corporations, partnerships, and LLCs taxed as S corporations or partnerships)
If your business is an S corporation, partnership, or an LLC taxed as an S corporation or partnership, and you filed a tax extension by March 15, 2025, you have until September 16, 2025 to make both employer and employee contributions to your Solo 401k.
📌 October 15, 2025
Extended Contribution Deadline
(For C corporations, sole proprietorships, and LLCs taxed as sole proprietorships)
C corporations, sole proprietorships, and LLCs taxed as sole proprietorships can make employer and employee contributions until October 15, 2025 if they file a tax by March 15, 2025.
📝 Important: This article is for informational purposes only and does not constitute tax, legal, or financial advice. Always consult a qualified tax professional or financial advisor before making decisions about your Solo 401k plan.
Frequently Asked Questions
When Is the Deadline to Set Up a Solo 401k?
If you wish to set up a Solo 401k plan for the 2024 tax year, you generally must establish a plan by the last day of the year (December 31, 2024). Since the deadline falls during the holiday season, it’s best to complete the setup a few days earlier to avoid any last-minute issues. The same rule typically applies for future years, including 2025 — December 31 is the key deadline to keep in mind.
If you operate as a sole proprietorship, you have until April 15, 2025 to open a Solo 401k plan and make your contributions for the 2024 tax year. However, no extensions would be allowed in this case.
📌 Set up a plan with Carry in a few clicks, or compare the best Solo 401k plan providers here.
When Is the Last Day to Make Solo 401k Contributions?
✅ For S corporations, partnerships, and LLCs taxed as S corporations or partnerships
- Contribution deadline: March 15, 2025
- With an extension: September 16, 2025
✅ For C corporations, sole proprietorships, and LLCs taxed as sole proprietorships
- Contribution deadline: April 15, 2025
With an extension: October 15, 2025
How Much Can I Contribute to My Solo 401k?
For the 2024 tax year, you can contribute up to $69,000 to your Solo 401k across both employee and employer contributions. If you turn 50 or older by December 31, 2025, you’re allowed an additional $7,500 in catch-up contributions, bringing your total to $76,500.
What’s the Difference Between Employee and Employer Contributions?
With a Solo 401k plan, you have full control over both your employee and employer contributions. These contributions have different limits and are treated differently for tax purposes.
✅ Employee Contributions (Elective Salary Deferrals)
- Represent a portion of your earnings contributed to your Solo 401k rather than kept in your personal account (even if you don’t receive a formal salary as a self-employed individual).
- You can contribute up to 100% of your compensation, with a maximum of $23,000 ($30,500 if age 50+) for the year 2024 and $23,500 ($31,000 if age 50+) for 2025.
- Can be made as pre-tax or Roth contributions.
✅ Employer Contributions (Profit-Sharing)
- Separate from your salary, these are additional contributions made by the business directly into your Solo 401k.
- If your business is incorporated, you can contribute up to 25% of your compensation.
- If your business is not incorporated, you can contribute up to 20% of net earnings.
- Employer contributions can only be made as pre-tax contributions.
The combined employee and employer contributions must not exceed the Solo 401k limit for each tax year. For 2024, the maximum contribution is $69,000 ($76,500 if you’re 50 years old and above). In 2025, this limit increases to $70,000 ($77,500 for those 50 and older).
📌 Also read: Solo 401k Contribution Types Explained
Is There a Deadline to Rollover Funds into a Solo 401k?
There is no deadline to transfer assets from another retirement plan into your Solo 401k.
✅ No Limit on Rollover Amounts — You can rollover any amount from another retirement account without restriction.
✅ Does Not Affect Contribution Limits — Rollovers are separate from annual contribution limits, meaning they won’t count toward your Solo 401k contribution cap for the year.
Do I Need to Be Aware of Any Tax Forms?
Yes! If you have a Solo 401k, here are the key tax forms to know:
- Form 5500-EZ: Required if you’re closing your Solo 401k plan or have $250,000+ in plan assets. However, at Carry, we recommend filing From 5500-EZ every year, regardless of plan assets.
- Form 1099-R: Required whenever funds/assets are moved out of your Solo 401k account, including distributions, rollovers, in-plan conversions, or RMDs.
- Form 945: Required when you take an early distribution from your Solo 401k in order to report the 20% tax withholding.
- Form 8606: Required when you use a non-deductible IRA to rollover to a Roth solo 401k.
📌 Also read: Important Forms for Solo 401k Owners
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.
Eligibility for a Solo 401(k) is subject to specific IRS requirements. Not all business owners or individuals with side income will qualify. The maximum contribution limit of $70,000 (or $77,500 for those age 50 and over) for 2025 is not universally applicable and depends on factors such as your earned income, age, and specific plan details. Please consult with a tax professional to determine your eligibility. Tax deductions and growth are subject to IRS rules and regulations. Withdrawals from traditional 401(k) accounts are generally taxed as ordinary income when distributed. Borrowing from your 401(k) may have significant tax consequences and could impact your retirement savings. Loans must be repaid according to IRS guidelines. Individual Plan administrators are responsible for ongoing compliance of all plans on Carry’s platform.
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 brochure and Form CRS or through the SEC’s website at www.adviserinfo.sec.gov.