Why can't I use the same email address on my client account that is on my advisor account?

Übersicht: 

When attempting to create sub accounts for themselves, many advisors cannot complete the process due to the client email address matching that of the advisor.

Information:

As a measure of client protection, IBKR will not allow the e-mail address of a client to match that of the Advisor.

A popular option is to create a new e-mail address for yourself, using a free service such as Gmail.

This will allow you to create the new sub account.