
A 401k is a type of retirement plan that many employers offer to their employees. It's a great way to save for your future, but it can be confusing if you've never worked with one before.
The goal of a 401k is to help you save for retirement by setting aside a portion of your paycheck before taxes are taken out. This can reduce your taxable income and help you grow your savings over time.
You can contribute to a 401k through payroll deductions, which means your employer will take the money out of your paycheck before you even see it. This makes it easy to save for retirement without having to think about it.
Related reading: How Much per Paycheck to Max 401k
Retirement Plans
If you're looking to set up a retirement plan, you've got options. A one-participant 401(k) plan, also known as a Solo 401(k), is a type of plan that's available to business owners with no employees, or just themselves and their spouse.
These plans have the same rules and requirements as any other 401(k) plan. The business owner wears two hats in a 401(k) plan: employee and employer. Contributions can be made to the plan in both capacities.
Here are some common names for a one-participant 401(k) plan:
- Solo 401(k)
- Solo-k
- Uni-k
- One-participant k
Performance
The C Fund's performance is a crucial aspect to consider when evaluating its effectiveness as a retirement plan. The fund's average annual returns are not specified for YTD, 1 year, 3 years, 5 years, and 10 years.
The fund has a total expense ratio of 0.048% (4.8 basis points), which is a relatively low fee compared to other investment options. This low fee can help maximize your returns over time.
The C Fund is designed to replicate the performance of the S&P 500 Index, which tracks the performance of major U.S. companies and industries. The S&P 500 Index is an index of 500 large to medium-sized U.S. companies that are traded in the U.S. stock markets.
The fund's asset manager is BlackRock Institutional Trust Company, N.A., and State Street Global Advisors Trust Company, who are responsible for selecting, purchasing, investing, and managing the fund's assets. The C Fund holds all the stocks included in the S&P 500 Index in virtually the same weights that they have in the index.
Here are the fund's sector weights:
Employer Contributions
As the business owner, you have the flexibility to make profit sharing contributions to your solo 401(k) plan. This means you can contribute a portion of your business income to the plan, but it's essential to understand the rules and limits.
You can make profit sharing contributions up to 25% of your compensation for S-Corporations, C-Corporations, Partnerships, and Multi-member LLCs. This is a significant advantage of having a solo 401(k) plan, as you can contribute more to your retirement savings.
However, if you're a sole proprietor or single member LLC owner, the rules are slightly different. Your profit sharing contributions are limited to 25% of your income that's subject to self-employment tax. But, because you can deduct half of your total self-employment tax, not all of your self-employment income will be subject to self-employment tax.
To make things clearer, the IRS provides a step-by-step worksheet for this calculation in publication 560. You can also use a calculator from Bankrate.com to help with the math.
Take a look at this: 401k Employment Termination
In general, your total contributions, including employee deferrals and employer profit sharing contributions, may not exceed $57,000 if you're under 50 years old. If you're 50 or older, your aggregate limit rises to $63,500 with the $6,500 of catch up contributions.
Here's a summary of the profit sharing contribution limits for different business entities:
Remember, these limits apply to your total contributions across all 401(k) plans you participate in, so it's essential to keep track of your contributions to avoid exceeding the limits.
Setting Up a Solo 401(k)
You can establish a solo 401(k) by December 31st of the tax year you'd like to contribute for.
Most brokerage firms offer solo 401(k) plans at very low annual costs, making it a straightforward process.
To implement a solo 401(k) plan, you'll need to establish it by the December 31st deadline.
You can deposit elective deferrals any time before your tax filing deadline, which is usually April 15th for sole prop's and single member LLCs.
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Elective deferrals must be reported on your W-2 by January 31st, and your bookkeeper or accountant can handle the reporting for you.
Profit sharing contributions can be made any time before your tax filing deadline, plus extensions.
You'll claim the deduction for the contribution on either your business or personal return.
If your solo 401(k) has assets over $250,000, you'll need to file form 5500 SF with the department of labor.
Here's a summary of the key deadlines to keep in mind:
- December 31st: Establish a solo 401(k) plan
- April 15th (or March 15th for multi-member LLCs, partnerships, and S-Corps): Elective deferral deadline
- January 31st: Report elective deferrals on W-2
- April 15th (or March 15th, or September 15th, or October 15th): Profit sharing contribution deadline
Eligibility and Contributions
To be eligible to contribute to a solo 401k, you typically need to have self-employment income, which could be from working as a 1099 independent contractor or running a sole proprietorship, partnership, or LLC.
Solo 401k plans are most often used by sole proprietors and single member LLCs, as having eligible employees prevents businesses from using them. However, they can also be used in partnerships, multi-member LLCs, S-corporations, and C-corporations as long as there are no qualifying employees.
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The amount you're allowed to contribute to a solo 401(k) plan depends on your business entity and net income from self-employment.
Here are the contribution limits for a solo 401(k) plan:
- Employee contributions: up to $19,500 ($26,000 if 50 or older) in 2020
- Employer contributions: up to 25% of compensation for S-Corporations, C-Corporations, partnerships, and multi-member LLCs; up to 20% of earned income for sole proprietors and single member LLCs
Your total contributions in 2020 may not exceed $57,000 if you're under 50 years old, or $63,500 if you've reached 50 with catch-up contributions.
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Contribution Limits for Single Participant Plans
Contribution limits in a single participant 401(k) plan are quite straightforward. You can make elective deferrals up to 100% of your compensation, up to the annual contribution limit.
The annual contribution limit for 2024 is $69,000, and it's $66,000 for 2023, $61,000 for 2022, $58,000 for 2021, and $57,000 for 2020. This limit applies to total contributions, not counting catch-up contributions for those 50 and over.
As a business owner with no employees, you're free to make profit sharing contributions for yourself only, up to the IRS limits. The limit depends on your business entity, and for S-Corporations, C-Corporations, Partnerships, and Multi-member LLCs, it's 25% of your compensation.
Consider reading: 401k S and P Index Only Startegy
For sole proprietorships and single member LLCs, the limit is slightly more complex. It's limited to 25% of the business owner's income that's subject to self-employment tax. However, because sole props and single member LLCs are entitled to deduct half of their total self-employment tax, not all self-employment income will be subject to self-employment tax.
Here's a breakdown of the contribution limits for single participant 401(k) plans:
Keep in mind that these limits apply to total contributions, not counting catch-up contributions for those 50 and over. If you've exceeded the limit for elective deferrals, you can find out how to correct this mistake in the relevant IRS publication.
Other Eligibility Issues
To be eligible to contribute to a solo 401k, you don't need a lot of income or a big business - just self-employment income will do.
You can have a 1099 independent contractor job, or work as a sole proprietorship, partnership, or LLC.

Solo 401k plans are most often used by sole proprietors and single member LLCs because they typically have few or no employees.
Even if you have a partnership, multi-member LLC, S-corporation, or C-corporation, you can still use a solo 401(k) as long as you have no qualifying employees.
The exact amount you can contribute to a solo 401(k) plan depends on your business entity and net income from self-employment.
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Examples and Maintenance
The contribution limits to solo 401(k)s can be tricky.
Solo 401(k)s allow business owners to contribute up to 20% of their net earnings from self-employment to their retirement accounts.
In some cases, solo 401(k) contribution limits may be affected by other sources of income, such as a spouse's income.
If you're self-employed and have a spouse who also earns income, you may need to consider their income when calculating your solo 401(k) contribution limit.
The contribution limits for solo 401(k)s are determined by the IRS and can change from year to year.
You should review the current contribution limits and adjust your contributions accordingly to avoid over-contributing and facing penalties.
A different take: 401k Beneficiary Rules Surviving Spouse Fidelity
Frequently Asked Questions
What are the three types of 401k?
There are three main types of 401(k) plans: traditional, safe harbor, and SIMPLE 401(k) plans, each with its own set of rules for tax-favored status. Understanding the differences between these plans is essential for employers to set up a compliant and effective retirement savings plan.
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