I´m working on a new website. This site has a front-end part, which is about the company, etc, and then the users could log in and go to an intranet site with the information about their accounts. My question is: Should I open that dashboard in a new tab or can I let the user log in to the same page and add the dashboard options after they log in but all in the same page?
I can't think of a well known website that opens a different tab in your browser as part of the login process (correct me if I'm wrong here). If you do a login action on a specific page, any extra content you have access to is normally displayed in addition to what was previously available on that page, and in that browser tab.
If the login is taking the user to something that is conceptually a completely different site (in this case I think it might be), then it is fine to go to a different page in a different browser tab, but I would open the new browser tab before displaying the login form. The original page should just contain a button / link to the intranet.
The question is, does the user who logs in really care about having quick access to the content on the "about page"? If not then why leave it open?