Inherited account

I inherited a 401k from my mother who passed away. Her current financial institution told me that they could not authorize a rollover and that it would need to be cashed out. Can this inherited account be rolled over into my Solo 401k plan?

A 401k that you inherited cannot be rolled over into your Solo 401k or personal IRA. It can only be rolled over into an inherited IRA, which is set up in the name of the deceased with you as the beneficiary.

Inherited IRAs are still subject to RMDs:

https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-beneficiary

For further guidance on inherited IRAs, please consult with your CPA.