In version 10.0.34 Financial tags appear on more journals and documents. Financial tags have been added to the following journals: Periodic journal, Fixed asset journal, Allocation journal, Reporting currency adjustment journal, Vendor invoice journal, Invoice register, and Vendor approval journal.
Financial tags first surfaced in version 10.0.32. Financial tags are user-defined fields used to track additional information on accounting entries, necessary for analytics or processes that occur against the accounting entries. Up to 20 financial tags can be created to track information such as: Customers, Vendors, Projects, Purchase order numbers or a Payment reference. Financial tags should be considered as an alternative to creating financial dimensions in order to track data on the accounting entries.
For more information see https://learn.microsoft.com/en-us/dynamics365/finance/general-ledger/financial-tag and https://learn.microsoft.com/en-us/dynamics365/finance/general-ledger/financial-tag-financial-dimension