Solo 401k Plans | Fidelity Solo 401k Trust Checkbook

QUESTION: On the top of the Fidelity check writing form it says to use this form for non-retirement accounts?? Isn't a solo 401k a retirement account?
Thanks, OR

ANSWER: Fidelity uses the non-retirement account terminology to denote that they are not the trustee/fiduciary/administrator of the Solo 401k since they also offer Solo 401k plans that only allow you to invest in stocks and mutual funds.

However, Fidelity also offers brokerage accounts for 401k plans including Solo 401k whereby Fidelity is not the solo 401k provider, trustee, administrator or fiduciary, which is the type of account that needs to be opened in this case.  In short, just like at the bank level where the bank would be providing a bank account for the solo 401k trust, under this scenario Fidelity is providing a brokerage account with checkbook feature for the Solo 401k trust brokerage account.