Thank you for reaching out to Microsoft Q&A forum
Based on your description, I understand that you want to implement automatic metadata tagging for files uploaded to SharePoint, but with the strict requirement that the tags must come exclusively from your organization's own controlled/custom tag list (typically a Term Store term set or a predefined list of allowed values), and never from any external/public AI suggestions or internet-sourced keywords.
In this context, I recommend you consider trying SharePoint Premium Taxonomy Tagging approach. This is the natively and most widely adopted solution today. That said, you can follow below instructions to do this:
1/ Prerequisites & Billing Setup
Requires SharePoint Premium pay-as-you-go (formerly Syntex) via Microsoft 365 admin center → Settings → Org settings → Pay-as-you-go services → Settings -> Document & image services → Taxonomy tagging → Link Azure subscription.
Link references: Set up and manage taxonomy tagging
Free trial quota details (still active in December 2025)
2/ Prepare Your Custom Tag List in the Term Store
- Go to Microsoft Purview portal or SharePoint admin center → Content services → Term store.
- Create or use an existing term set then enrich every term with synonyms, descriptions, and (highly recommended) pin 3–10 representative sample documents per term
3/ Enable Taxonomy Tagging on the Target Document Library
- Add (or use existing) Managed Metadata column connected to your term set.
- Edit the column → under “Automatically tag documents with terms” → toggle to Yes.
- Maximum 5 taxonomy-tagging-enabled columns per library.
Link reference: https://learn.microsoft.com/en-us/microsoft-365/documentprocessing/taxonomy-tagging?view=o365-worldwide
New or edited files are processed automatically (usually within minutes to a few hours). For existing files: bulk-edit in grid view (just open and close) or use Power Automate to “touch” them.
Hope my answer will help you, for any further concern, kindly let me know in the comment section.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.