Solo 401k where spouse owns business

[Todd Goedeke]

Example, husband and wife each own a company. Husband has a widget company with W-2 employees working over 1,000 hrs/ yr. His W-2 earnings are 180k. He has a 401k for himself and employees.

His wife has a profitable small business that has no employees and has no business dealings with her husband s company. She is not an employee of her spouse s company. She wants to open a Solo 401k. Can she open a Solo 401k without falling under "control group" rules?

I understand both her and husband can contribute and rollover IRAs to their respective accounts in the Solo 401k. Then they my use Roth backdoor  policy to convert IRAs to Roth .