With a traditional 401(k) plan, you're legally responsible for:
Operational Defects
The plan document provides the framework for the day-to-day operation of your plan. But all too often, it gets filed away and forgotten about because you are busy running your business and who has time to read such a complicated document anyway? Unfortunately, in the eyes of the regulators, you are ultimately responsible for keeping your plan in compliance with the terms of your document, and failure to do so can result in penalties or even disqualification of your plan.
Plan Investments
Most plans allow participants to make their own investment choices but it is the plan sponsor’s responsibility to take steps to regularly make participants aware of their rights and responsibilities under the plan related to directing their investments.
Department of Labor Audits
If you're audited by the Department of Labor, you're liable for any operational defects found across your entire plan. When you outsoruce your fiduiary liability, that becomes someone elses concern.
Right now, you’re responsible for all of this. With a Named 402(a) Fiduciary, you won't be anymore.