Zendesk's tags behave a little differently than other tools in that a ticket may "collect" tags over the course of its life. Users and Organizations are allowed to have tags. A ticket will automatically pick up the tags of a particular user and their org when the ticket is created.
Additionally, when creating new custom dropdown fields or checkboxes, they can be configured to automatically add a tag to the Organization, User, or Ticket.
Because tags are so flexible, we generally suggest you use dropdowns and checkboxes for most Census data sync designs.