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Answered By: Robert Harvey
Last Updated: Aug 25, 2025     Views: 871

Microsoft Authenticator is the application/service Fairfax County uses for Multi-Factor Authentication (MFA) to verify and authenticate staff. This is required for staff who are using https://portal.office.com inside County facilities as well as those accessing the county network and applications on non-County devices or for users accessing from home or away from the office. Instructions for installing MS Authenticator may be found here. A video of the steps involved may be found here.

Tips include:

  • Registering Authenticator from inside a library branch on the county network
  • If you have previously used Authenticator, it is very helpful to have the old phone available to register a new device.


From portal.office.com, click your account in the bottom left and select View Account