Contribution Types: Self-Directed 401k | Self-Directed Solo 401k | Solo 401k |Solo K

A solo 401k, often referred by various names such as self-directed Solo 401k plan, self-directed 401k or solo K, allows for various types of contributions as described below.

Contribution Types

  1. Employer profit sharing contributions
  2. Pretax employee salary deferral contributions
  3. Roth designated employee contributions
  4. Employee voluntary after-tax contributions

Total Contribution Limit

Each contribution types have separate limits, and, when combined, cannot exceed the maximum solo 401k contribution amount which is $58,000 per year or $64,500 for those 50 or older in 2021. For tax year 2022, the maximum contribution that can be made to a solo 401k pan is 61,000 plus $6,500 if you are age 50 or older in 2021.

My Solo 401k Financial Solo 401k Contribution Features Types

Solo 401k Contribution Types Explained

Employer profit sharing contributions

  • In accordance with IRC Sec. 404 the profit sharing contribution cannot exceed 25% of income derived from business activity (earned income NOT passive income).
  • Salary deferral contributions are not included with profit sharing contributions when calculating the 25 percent deductible contribution.
  • If the owner-only business participant has enough net income from self-employment activity, she can treat the entire contribution as a profit sharing contribution which is fully tax tax deductible. Note, however, that employee contributions are not part of the employer profit sharing contribution source; therefore, the catch up contribution applicable to those participants age 50 or older cannot be treated as am employer profit sharing contribution.

Example: Janice wants to make profit sharing contributions to her solo 41k for tax year 2021. Janice is age 56, has already made the full employee contribution of $19,500 to her day-time job 401k, and wants to maximize her employer profit sharing contribution to her solo 401k which she setup for her self-employed business.  Janice had a good year being self-employed under her S-corporation and received $250,000 in W-2 wages from her self-employed business so she wants to reduce her taxable income for the year by making profit sharing contributions. Based on $250,000 of W-2 wages from her self-employed business, the maximum profit sharing contribution that Janice may make to her solo 401k for 2021 is $58,000.  Because the catch up contribution of $6,500 falls under the employee contribution source not the employer profit sharing contribution source, she cannot make the catch up contribution to her solo 401k plan unless she elects to treat it as an employee contribution which she can technically elect to do since she did not make it to her day time job employer  401k.

  • Profit sharing contributions are not required to be made each year.

Pretax employee salary deferral contributions

  • Pretax employee salary deferral contributions found under IRC Sec. 402(g) permits business owners to contribute up to 100 percent of compensation not to exceed $19,500 to the solo 401k plan for 2021, or $20,500 for tax year 2022.
  • The rules also allow for catch-up contributions provided you are age 50 or older. Per IRC Sec. 414 (v), if the business owner has the applicable self-employment earned income, she can make additional catch amounts of $6,500 for 2021 if age 50 or older. The $6,500 employee catchup remains the same for 2022.

Roth designated employee contributions

  • Since 2006, the self-employed  have been allowed to treat all or some portion of their salary deferral limit (the $19,500 in 2021, or $20,500 in 2022) as designated Roth solo 401(k) contributions.
  • The designated Roth solo 401k contributions are outlined in IRC Sec. 402A, and treated as after-tax contributions (that is, you cannot take a tax deduction on your taxes for the contribution).
  • The flip side is that all earnings resulting from the Roth solo 401k contributions can be distributed tax-free.
  • Roth solo 401k annual contributions  cannot exceed the $19,500, plus the $6,500 catch-up contribution if age 50 or older for 2021. For 2022, the Roth solo 401k contribution is $20,500 plus the $6,500 catch up contribution for those age 50 or older.

Employee voluntary after-tax contributions

  •  With the exception of the catch up solo 401k contribution which can be made by those age 50 or older, the solo 401k participant can elect to treat part or all of her solo 401k contributions to as voluntary after-tax solo 401k contribution.  Therefore, if you have enough earned income from self-employment activity, regardless if you already make contributions to your day-time job 401k plan, 403b or 457 plan, you can contribute the full $58,000 allowable contribution to your voluntary after solo 401k bucket for tax year 2021, or $61,000 for tax year 2022.
  • Jut like Roth solo 401k contributions, voluntary after-tax solo contributions are not excluded from income and the owner only business participant cannot deduct them on his or her tax return.
  • The voluntary after-tax solo 401k bucket only allows for employee contributions not employer profit sharing contributions.
  • Making voluntary after-tax solo 4o1k contributions is a good way to indirectly super charge your Roth funds whether Roth IRA or Roth 401k funds. Reason being, the voluntary after-tax funds can immediately be converted to a Roth IRA to internally to the Roth solo 401k bucket.

Solo 401k Annual Contribution Tidbits

  • All solo 401k contributions cannot be subject to a vesting schedule so are always 100 percent fully vested.
  • Rollover contributions are also always vested.
  • Provided a triggering event occurs such as age 59 1/2 and no longer being self-employed, Roth solo 401k contributions can be transferred to a Roth IRA or a full-time employer plan such as a Roth 401k, Roth TSP, Roth 457b,  and Roth 403b.

Number of Holding Accounts QUESTION:

If I choose to rollover from after-tax contributions to my existing Roth IRA in Vanguard, do I just need to open two subaccounts ie, pretax and aftertax? Do I have the option to open Roth 401k subaccount at a later date if I decide to contribute to Roth 401k directly?

Correct the voluntary after-tax solo 401k contributions can be converted to a Roth IRA thereby not requiring a Roth solo 401k account at this time. You can later open the Roth solo 401k account as solo 401(k) already allows for all three contribution types— that is, pretax, Roth, and  voluntary after-tax.

About Mark Nolan

Each day I speak with energetic entrepreneurs looking to take the plunge into a new venture and small business owners eager to take control of their retirement savings. I am passionate about helping others find their financial independence. Having worked for over 20 years with some of the top retirement account custodian and insurance companies I have a deep and extensive knowledge of the complexities of self-directed 401ks and IRAs as well as retirement plan regulations. Learn more about Mark Nolan and My Solo 401k Financial >>


  • Popular Video

  • ROBS 401k Funding Process

  • Solo 401k Contributions Including Mega

  • Checkbook IRA LLC

  • About MySolo401k

    We help our clients take control of their retirement money. Our products and services provide our clients the freedom to invest their retirement savings in their own business as well as alternative investments such as real estate, private companies, promissory notes, precious metals, tax liens and equities.
    Learn more

    Connect with us

  • We’re here to help.

    Call: 800-489-7571


    8:00 am - 4:00 pm PT

    Why us?