Can my wife transfer her retirement funds to my Solo 401k plan?

No, she cannot rollover her retirement funds into your account within the Solo 401k.

Only participants in the Solo 401k can rollover funds from their retirement accounts into the Solo 401k. If you are the only participant in the Solo 401k, only you can rollover funds into the plan.

Your wife can participate in the Solo 401k if she is also employed by the adopting business of the plan. If she is eligible to participate, she can be added to the plan, create her own account(s) within the Solo 401k, and roll her retirement funds into it.

Spousal participation