You will name a successor trustee when you sign up for an account.
If you are using a Self-Directed Solo 401(k) account, your assets will be held in a trust. The successor trustee will take over assets in the trust in the event of your death, and he or she is responsible to ensure that your property is distributed to your beneficiaries according to the terms of the trust.
The successor trustee and the beneficiary for your Solo 401(k) can be the same person, but keep in mind they are separate in legal definition.
You can request a beneficiary appointment form by contacting Support. Once you name beneficiaries, keep this document with your will and estate plans or your successor trustee. In the event of your death, your successor trustee would help execute it.
After you die, your successor trustee is the executor of your estate. They pay your final bills, sell assets if needed, work on your final tax return, and most important, distribute your assets according to the instructions detailed in your trust.
Keep in mind that if you are delaying when your assets can be distributed, your successor trustee will have to pay attention to your trust for a longer period of time or need to seek special assistance with the assets inside the trust. It would be wise to leave them instructions and resources as to who and which organizations they can talk to.