Hi,
Thanks for reaching out to microsoft q&a.
Tag is a best practice but for identification and responsibility. In your case Tag's will be useful to track and calculate the expenses according to cost center. You will have to make sure all the resources that are created are tagged, there might be some users who don't or forgot to do that. In those cases you can set policy definition; more details on the below link.
https://learn.microsoft.com/en-us/azure/azure-resource-manager/management/tag-policies
Please upvote or accept as answer if this is useful to you.