definition

A qualified retirement plan designed specifically for business owners with no full-time employees,  other than a working or non-working spouse.  Solo 401(K) rules apply.

commentary 

The solo 401(k) allows for higher contributions than other common retirement plans traditionally used by single-owner businesses,  such as SIMPLE and SEP plans.  The administration of the plan is very simple, especially when the plan balance is under $250,000,  and it can be designed with traditional or Roth tax treatment.  This makes the Solo 401(k) a flexible, powerful tool.