I'm planning to open a Solo 401(k) with Schwab. There are some provisions that are decided by the Plan Administrator, which I assumed would be me (my business, technically). However, doing research, I've found that there are Third-Party Administrators, there are brokers, there are custodians....and I could be my own administrator with a Self-Directed or Prototype plan.
Needless to say, I'm a little confused.
My question: for the terms "Administrator", "Broker", and "Custodian", what are the formal definitions in the context of a 401(k) plan? What are the duties and responsibilities of each? Is there any overlap?
I believe that with some extra clarity, I can figure out what I can do myself (perhaps I can be the plan administrator if it only requires tax documentation and nothing else) and what I need to look for. (If being an administrator is a larger burden, I want to see whether Schwab will shoulder that or whether I need to find something else.)