How to Use Notion Relation for Tag Taxonomy Across Multiple Databases

Notion databases let you store and organize information, but when you need the same set of tags to work across several databases, a simple multi-select property falls short. Each database with a multi-select property has its own isolated list of tag values, so updating a tag in one database does not change it in another. This article explains how to use Notion’s Relation property to build a centralized tag taxonomy that syncs across multiple databases, eliminating duplicate tag management and keeping your data consistent.

What Is a Tag Taxonomy and Why Use Relation Instead of Multi-Select

A tag taxonomy is a controlled vocabulary of labels — for example, “Urgent”, “Design”, or “Client A” — that you assign to items to categorize them. In Notion, a multi-select property lets you create tags quickly, but each database keeps its own tag list. If you have three databases (Projects, Tasks, and Notes) and want to use the same tag “Urgent” in all of them, you must add that tag separately to each database. Renaming or deleting the tag requires editing every database manually.

Using a Relation property solves this by creating a link between a content database and a dedicated Master Tag Database. Each tag is a page in the Master Tag Database. When you assign a tag to an item, you create a relation link to that tag page. Any change to the tag page — renaming, adding a description, or changing a color — is immediately reflected everywhere the tag is used. This approach also lets you add metadata to tags, such as a category or a priority level, which a multi-select property cannot do.

Prerequisites for Building a Tag Taxonomy

You need at least two databases: one Master Tag Database and one content database (or more). Both databases must be in the same Notion workspace. A Notion account on any plan supports Relation properties. If you want to display the tag name in the content database view without opening the tag page, you will also use a Rollup property.

Steps to Create a Relation-Based Tag Taxonomy

Follow these steps to set up a centralized tag taxonomy that works across multiple content databases.

1. Create the Master Tag Database
   Create a new database in Notion. Name it “Tags” or “Master Tags”. Add a Title property for the tag name. Optionally, add a Select property for a color or category. Each page in this database will represent one tag, such as “Urgent”, “Design”, or “Client A”.
2. Add tags as pages in the Master Tag Database
   Open the Master Tag Database and click New to create a page for each tag you need. Set the page title to the tag name. You can add a cover image or description if desired. Repeat for all tags.
3. Add a Relation property to your content database
   Open your content database (for example, “Tasks”). Click the + icon in the database header to add a new property. Select Relation from the property type list. In the dialog that appears, choose the Master Tag Database (“Tags”) as the related database. Name the property “Tags” or “Label”. Click Create Relation.
4. Configure the relation to allow multiple tags
   After creating the relation, click on the property name in the database header. In the property settings, enable “Allow multiple relations”. This lets you assign more than one tag to a single item. If you only need one tag per item, leave this option disabled.
5. Assign tags to content items
   Click the Relation property cell for any row in your content database. A menu opens showing all pages from the Master Tag Database. Select one or more tags. The selected tag pages now appear as links in the cell. You can click a tag link to open the tag page and edit its details.
6. Add a Rollup property to display the tag name (optional)
   If you want to see the tag name as plain text instead of a link, add a Rollup property. Click + in the database header, select Rollup. Name it “Tag Name”. Set the Relation property to the Tags relation you created. Set the Property to “Name” (the title property of the Master Tag Database). Set the Rollup calculation to “Show original”. The tag name now appears as text in each row.
7. Repeat the relation setup for additional content databases
   For each additional database (such as “Projects” or “Notes”), repeat steps 3 through 6. Create a Relation property pointing to the same Master Tag Database. All content databases now share the same tag taxonomy.

Common Mistakes and Limitations to Avoid

Even with a well-designed relation setup, some pitfalls can break your tag taxonomy. Here are the most frequent issues and how to avoid them.

Accidentally Deleting a Tag Page Breaks All Relations

When you delete a tag page from the Master Tag Database, every relation link pointing to that tag becomes broken. The cell in the content database will show a blank or missing link. To avoid this, do not delete tag pages — instead, archive them or add a status property to mark them as inactive. If you must delete a tag, first remove all relations that reference it in every content database.

Relation Property Shows Only the Tag Page Title, Not Custom Properties

The Relation property displays the title of the linked page. If you add other properties to the tag page (like a color or description), those are not shown in the relation cell. Use a Rollup property to pull additional data from the tag page, such as a Select color or a formula. For example, create a Rollup that shows a “Color” property from the Master Tag Database.

Cannot Filter by Tag Color Directly in Content Database

If you store a color in the Master Tag Database as a Select property, you cannot filter the content database by that color directly. You must first create a Rollup that pulls the color value into the content database, then filter by that Rollup column. This adds an extra step but keeps your tag metadata centralized.

Relation Links Are Not Editable in Bulk

Notion does not provide a built-in way to replace one tag with another across all items in a content database. If you need to rename a tag, edit the tag page title in the Master Tag Database — all relations automatically update. If you need to merge two tags, you must manually reassign each item that uses the old tag to the new tag page, then delete the old tag page.

Relation-Based Tag Taxonomy vs Multi-Select Tags: Compared

Item	Relation-Based Tag Taxonomy	Multi-Select Tags
Centralized tag list	Yes — all tags in one database	No — each database has its own list
Rename a tag globally	Edit one tag page — all relations update	Must edit each database separately
Add metadata to tags	Yes — add properties like color or category	No — tags have no extra properties
Assign multiple tags per item	Yes — enable “Allow multiple relations”	Yes — native multi-select behavior
Display tag name in view	Shows linked page title; Rollup needed for plain text	Shows colored tag bubble directly
Setup complexity	Moderate — requires creating a master database and relation	Low — add property and type tags
Best for	Multiple databases needing consistent tags and tag metadata	Single database with simple, isolated tagging

Now you have a centralized tag taxonomy that works across all your content databases. Start by creating your Master Tag Database and defining your tag pages. Then add a Relation property to each content database and connect them. To keep your tags organized, use a formula property in the Master Tag Database to automatically generate a slug or ID for each tag.