I have not made several mistakes. I have an approximately 3% stake in Company #1. I wholly own company #2. Company #1 I make only profit sharing contributions to the 401k which is $345k x .20 = $69000.
For Company #2, I make my elective contributions of $30,500 plus 20% of my income which amounts to about $12k in profit sharing.
With multiple 401k accounts, I know that the aggregate employee contribution cannot exceed $30,500 but you are allowed to place 20% profit sharing in each of the 401k accounts because they are not in a control group.
The IRS has an example of this on their website: https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-401k-and-profit-sha.... Example 1 shows how a person with two 401k accounts from unrelated employees can contribute to both plans. Elective deferrals are limited across all 401k plans, but profit sharing is not.
