What Is a Self-Employed 401(k) Plan?

Self-Employed 401(k) Plan Explained in Less Than 4 Minutes

Small business owners
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A self-employed 401(k) plan is a retirement plan for small business owners who are the only employee (besides a spouse) of their business. The small business owner can make contributions for both employee and employer.

Learn more about self-employed 401(k)s and how one can be used to plan for your retirement.

Definition of a Self-Employed 401(k) Plan

A self-employed 401(k) is a traditional 401(k) that sole proprietors and their spouses can set up to save for retirement. Since business owners work for themselves, they don't have an employer with an established pension plan, retirement fund, or plan to contribute to and take with them.

Alternate names: Solo 401(k) plan, one-participant 401(k) plan, uni-k, solo-k

How a Self-Employment 401(k) Plan Works

Self-employed 401(k)s allow small business owners with no other employees to contribute to a retirement plan as an employee and employer. This means that the same person makes both contributions.

There are two types of contributions made to 401(k) plans—elective deferrals and employer non-elective deferrals. Employees make elective deferrals and can include 100% of their compensation, up to the limit of $19,500 per year for 2021 and $20,500 for 2022. (These limits are frequently adjusted to account for cost-of-living increases.)

If the employee is 50 or older, they can make catch-up contributions of an additional $6,500 per year (totaling $26,000 per year for 2021 and $27,000 per year for 2022). The employer's contributions—called non-elective deferrals—can be a maximum of 25% of compensation after deductions calculated using tables and worksheets provided by the Internal Revenue Service (IRS).


Contribution limits are much higher for small business owners and their spouses, making the solo 401(k) an appealing retirement plan option over an IRA.

The result is that business owners can contribute a total of $58,000 to their 401(k) plan for 2021 and $61,000 for 2022. For business owners aged 50 or older, the total allowable annual investment is $64,500 for 2021 ($67,500 for 2022).

Once the plan is set up, business owners can make contributions for both themselves and their business. When they retire, they can make withdrawals and pay any necessary taxes.

A business owner and their spouse could then contribute a hefty $116,000 (employer plus employee contributions for both of them) to their retirement savings for 2021, earning interest and keeping that money protected from income taxes for decades.

For instance, a husband and wife set up a limited liability company and launch a small business when they're in their mid-20s. By the time they are 35 years old, they earn enough revenue to pay themselves $175,000 per year before taxes. They are the only employees of the holding company, so they can put $116,000 a year into their solo 401(k) plan.

The couple initially places $116,000 into their 401(k). They could continue to put that amount in their plan (adjusted for cost-of-living increases) but decide to reinvest it into their business, taking $75,000 per year for living expenses.


All 401(k)s are tax deferred until distributions are taken, which allows for extra interest-earning power.

Over the next 25 years, they earned 8% annually on their money and continued to invest $24,000 per year ($2,000 per month). Their combined 401(k) accounts would have more than $2.5 million waiting to fund their retirement.

If the couple continued to work as outlined in the example, all of that money would stay within the protected confines of the 401(k) account, earning dividends, interest, capital gains, and profits without them having to pay any income taxes until they began withdrawing from the plan.

Do I Need a 401(k) Solo Plan?

For sole proprietorship businesses, solo 401(k) plans are very effective ways to set aside and grow a large amount of money for retirement. If you're a small business owner and don't yet have a retirement plan set up, a solo 401(k) is an excellent way to save for retirement.

If you happen to need to hire employees at some time during your business's lifetime, you'll need to be sure to adjust the plan to include them equally or create criteria to define benefit-eligible employees and create retirement plans for them.

Key Takeaways

  • A solo 401(k) is a retirement plan for a small business owner and their spouse.
  • The business owner acts as the employer and employee for contributions.
  • Contribution limits essentially double for a business owner and spouse.
  • Continuous investing is what allows the money to compound so quickly in a 401(k).
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The Balance uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Internal Revenue Service. "One-Participant 401(k) Plans."

  2. Internal Revenue Service. "Retirement Topics - 401(k) and Profit-Sharing Plan Contribution Limits."

  3. Internal Revenue Service. "Publication 560 (2021), Retirement Plans for Small Business."

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