Impact of 403b Day-Time Job Contributions to Solo 401k Contributions including voluntary After-Tax Contributions

Last Updated 09/15/2022
If you participate in both a 403b plan through your day-time employer, and also participate in a solo 401k  sponsored by your self-employed business,  your annual contributions to both plans may be impacted as described below.

Employee Deferral Limit

The employee deferral limit –that is, the $20,500 for 2022 is aggregated across your day time employer 403b and your self-employed business solo 401k plan.
Therefore, you cannot make employee deferral limit contributions at the pretax and Roth solo 401k level if you have already maxed out the employee deferral limit to your day job employer 403b plan.

Voluntary After-Tax Solo 401k Contributions  Also Impacted

Just like employee pretax and employee Roth contributions to a 401k including a solo 401k are part of the 402(g) limit, they also apply to 403b annuity contracts. What is more, the 402(g) limit applies on a combined basis to elective deferrals made to a 401(k) plan and 403(b) plan .
As a result, the 403b annuity contract rules indirectly impact the ability to maximize the mega back door Roth solo 401k strategy.
The 403(b) annuity contact contributions are required to be aggregated with the contributions the self-employed individual makes to her solo 401k plan for purposes of the 415 annual additions limit.  This is due to the
special rule that applies to 403(b) annuity contracts where a participant
who is covered by the 403(b) plan is also in control of a separate company
(in this case, the participant’s self-employed business sponsoring the solo 401 k). In that case, the 403(b) contributions and  solo 401k contributions are required to be aggregated for purposes of applying the 415 limit.


A doctor is employed by a non-profit hospital to which section 501(c)(3) applies and which provides him with a section 403(b) annuity contract, and the doctor also maintains a private practice as a shareholder owning more than 50 percent of a professional corporation, then any qualified defined contribution plan (e.g., a solo 401k plan) of the professional corporation must be aggregated with the section 403(b) annuity contract for purposes of applying the limitations of section 415(c) and §1.415(c)-1.
In sum, the 403b annuity contribution aggregation rule is a 403b regulation not a solo 401k rule. It will be up to the 403b annuity contract provider to monitor the over contribution rules especially if the individual is also contributing to a solo 401k plan since this restriction is imposed by the 403b annuity rules not the solo 401k regulations.

W-2 Job & Solo 401k Eligibility QUESTION

I recently left my job and had a 403b with them. I do consulting work on the side and have a new W2 job? A few questions for you. 1. Even though I have a W2 job, am I still eligible for a solo401k? 2. Can I roll over some of my 403b into a solo401k?

One may certainly set up a Solo 401k based on their self-employment activity (and provided that there are no full-time w-2 employees working for their business) even if they have a w-2 job.
Moreover, such person can rollover funds from a former employer plan including a 403b and we will help guide through the transfer process as part of our services.

Amount of Self-Employment Income for Solo 401k Eligibility QUESTION

Does it matter how much self-employed income I make to be eligible for a solo401k?

There is no minimum self-employed income to qualify provided that such self-employment activity is legitimate and consistent (not just a one-time event).
See more:

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 >>


  1. Posted August 10, 2021 at 7:07 pm | Permalink

    Mark, my wife falls into this situation. She has contributed the max 19.5k at her daytime job (403b). Provided she has sufficient income, could she still contribute up to $58k directly into her solo 401k as an employer contribution (without labeling it voluntary after tax)?

  2. Posted August 21, 2021 at 8:12 pm | Permalink

    No, because of the aggregation rules.

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