Is a Solo 401(k) a new kind of 401(k) plan?

A Solo 401(k) plan is sometimes called a:

  • Solo-k or Solo-401(k)
  • Uni-k
  • One-participant k
  • Checkbook control Solo 401(k)

The Solo 401(k) plan is not a new type of 401(k) plan. It is a traditional 401(k) plan covering a business owner with no employees, or that person and his or her spouse. These plans have the same rules and requirements as any other 401(k) plan.

Contribution limits in a Solo 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. The owner can contribute both:

  • Elective deferrals up to 100% of compensation (“earned income” in the case of a self-employed individual) up to the annual contribution limit:
  • 2011: $16,500 or $22,000 if age 50 or over
  • 2012: $17,000 or $22,500 if age 50 or over; and
  • Employer non-elective contributions up to
    • 25% of compensation as defined by the plan, or
    • for self-employed individuals, see discussion below

Total contributions to a participant’s account, not counting catch-up contributions, cannot exceed $49,000 for 2011 and $50,000 for 2012.

Example: Ben, age 51, earned $50,000 in W-2 wages from his S Corporation in 2011. He deferred $16,500 in regular elective deferrals plus $5,500 in catch-up contributions to the 401(k) plan. His business contributed 25% of his compensation to the plan, $12,500. Total contributions to the plan for 2011 were $34,500. This is the maximum that can be contributed to the plan for Ben for 2011.

A business owner who is also employed by a second company and participating in its 401(k) plan should bear in mind that the limits on elective deferrals are by person, not by plan.

Contribution Limits for Self-Employed Individuals

You must make a special computation to figure the maximum amount of elective deferrals and non-elective contributions you can make for yourself. When figuring the contribution, compensation is your “earned income,” which is defined as net earnings from self-employment after deducting both:

  • one-half of your self-employment tax, and
  • contributions for yourself.

Use the rate table or worksheets in Chapter 5 of IRS Publication 560, “Retirement Plans for Small Business,” for figuring your allowable contribution rate and tax deduction for your 401(k) plan contributions.

Testing in a Solo 401(k) plan

A business owner with no common-law employees does not need to perform nondiscrimination testing for the plan, since there are no employees who could have received disparate benefits.

The no-testing advantage vanishes if the employer hires employees. No matter what the 401(k) plan is called by a plan provider, it must meet the rules of the Internal Revenue Code. If employees are hired and they meet the eligibility requirements of the plan and the Code, they must be included in the plan and their elective deferrals will be subject to nondiscrimination testing (unless the 401(k) plan is a safe harbor plan or other plan exempt from testing).

A Solo 401(k) plan is generally required to file an annual report on Form 5500-SF if it has $250,000 or more in assets at the end of the year. A one-participant plan with fewer assets may be exempt from the annual filing requirement.

Alternatives to a Solo 401(k) plan

Possible plans for a business owner include:

Most of the information on this page was taken directly from the IRS website:,,id=238750,00.html

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