Opening a Joint account is as easy as opening a new account!
If you're using a web browser, mouse over the Banking tab, then click "Open an Account". On mobile, tap the 3 dot menu and select Open An Account.
On Step One, select the Joint account option:
When you have this selected, you will be prompted to add more information about the additional owner. If this person is already added to your household, they will show up in this list. Otherwise you can add them by selecting New Person.
You will be prompted to enter their Email, Phone Number, and Relationship to You: make sure that the email address you enter has not been used to create a Personal Capital Dashboard. An invite will be sent to your joint owner at the email you enter, so make sure you have the email correct!
Once the invite is accepted your joint owner will be able to add funds to the account.