Each TaxAct Professional Edition user should create an account using first and last name, mailing address, and a unique email address. Once each account is set up, they can be linked together to form a practice. See the TaxAct Professional Getting Started Page
Practice Owner Account: TaxAct account used to purchase TaxAct Enterprise Edition. The Practice ID is assigned to this account. If you have multiple preparers in your practice, each preparer will have the same Practice ID assigned when they "join" the practice by entering the Practice ID during the Preparer Invitation Process.
Practice ID: Unique number assigned to Practice Owner account. Preparers "join" the practice by entering the Practice ID (a link in the invitation email will provide a prompt for this entry).
Linked Account: TaxAct account created by a preparer and invited to a practice by the Practice Owner. The account becomes linked to the practice when the invitation is accepted. A linked account cannot be the Practice Owner account.