Who can login to the Member Information Center
Ability to login to the Member Information Center is determined by permissions assigned in a rep's permission set.
Prior to our January 2014 Release, only those members who were also displayed in the public member directory were eligible for login to the Member Information Center. Since that software release, if the checkbox "Allow Login to MIC” is selected on the permission set assigned to the rep, then a rep will have access to the MIC limited to the permissions assigned to them.
For member logins, it is the "Enable Login" on the Web tab. Best practice would be to use the individual rep logins so that you have more control over the permissions that are granted.
Members with Prospective membership status will automatically have the Prospect permission set applied even if another permission set is displayed as their assigned permission set. This automatic default to the Prospect permission set gives fewer things to think about when moving a member to active membership status; the previously assigned permission sets of Primary, Billing and Standard will immediately begin applying without further action from you. So make sure when you setup a prospective member that the appropriate future permission sets are selected for the reps.
Of course, inactive members and reps will not be allowed access regardless of this checkbox. This change means that prospects, non-members, and courtesy members could have access to the MIC at your discretion without a requirement that they also display in the public member listing.