diff --git a/plugins/automation/config/locales/client.en.yml b/plugins/automation/config/locales/client.en.yml
index 5a7308f5831..aad7493d020 100644
--- a/plugins/automation/config/locales/client.en.yml
+++ b/plugins/automation/config/locales/client.en.yml
@@ -203,6 +203,14 @@ en:
             valid_trust_levels:
               label: Valid trust levels
               description: Will trigger only if post is created by user in these trust levels, defaults to any trust level
+        topic_tags_changed:
+          fields:
+            watching_categories:
+              label: Watching categories
+              description: Will trigger only if the topic is in one of these categories
+            watching_tags:
+              label: Watching tags
+              description: Will trigger only if the topic has any of these tags
         after_post_cook:
           fields:
             valid_trust_levels:
diff --git a/plugins/automation/config/locales/server.en.yml b/plugins/automation/config/locales/server.en.yml
index 98c6cb25577..19694ccfb3a 100644
--- a/plugins/automation/config/locales/server.en.yml
+++ b/plugins/automation/config/locales/server.en.yml
@@ -50,6 +50,9 @@ en:
       pm_created:
         title: Personal message created
         description: When a valid PM is created the automation will be triggered
+      topic_tags_changed:
+        title: Topic tags changed
+        description: When the tags of a topic are changed the automation will be triggered
       topic:
         title: Topic
         description: The associated script will only be used on the specified topic, this is usefull for scripts doing validation for example
diff --git a/plugins/automation/lib/discourse_automation/event_handlers.rb b/plugins/automation/lib/discourse_automation/event_handlers.rb
index 8ed26d28691..997a00c3eae 100644
--- a/plugins/automation/lib/discourse_automation/event_handlers.rb
+++ b/plugins/automation/lib/discourse_automation/event_handlers.rb
@@ -195,6 +195,36 @@ module DiscourseAutomation
         end
     end
 
+    def self.handle_topic_tags_changed(topic, old_tag_names, new_tag_names)
+      name = DiscourseAutomation::Triggers::TOPIC_TAGS_CHANGED
+
+      DiscourseAutomation::Automation
+        .where(trigger: name, enabled: true)
+        .find_each do |automation|
+          watching_categories = automation.trigger_field("watching_categories")
+          if watching_categories["value"]
+            next if !watching_categories["value"].include?(topic.category_id)
+          end
+
+          watching_tags = automation.trigger_field("watching_tags")
+          if watching_tags["value"]
+            should_skip = false
+            watching_tags["value"].each do |tag|
+              should_skip = true if !old_tag_names.empty? && !old_tag_names.include?(tag)
+              should_skip = true if !new_tag_names.empty? && !new_tag_names.include?(tag)
+            end
+            next if should_skip
+          end
+
+          automation.trigger!(
+            "kind" => name,
+            "topic" => topic,
+            "removed_tags" => old_tag_names,
+            "added_tags" => new_tag_names,
+          )
+        end
+    end
+
     def self.handle_after_post_cook(post, cooked)
       return cooked if post.post_type != Post.types[:regular] || post.post_number > 1
 
diff --git a/plugins/automation/lib/discourse_automation/triggers.rb b/plugins/automation/lib/discourse_automation/triggers.rb
index a1ad649d589..d1a0a1348fd 100644
--- a/plugins/automation/lib/discourse_automation/triggers.rb
+++ b/plugins/automation/lib/discourse_automation/triggers.rb
@@ -6,6 +6,7 @@ module DiscourseAutomation
     API_CALL = "api_call"
     CATEGORY_CREATED_EDITED = "category_created_edited"
     PM_CREATED = "pm_created"
+    TOPIC_TAGS_CHANGED = "topic_tags_changed"
     POINT_IN_TIME = "point_in_time"
     POST_CREATED_EDITED = "post_created_edited"
     RECURRING = "recurring"
diff --git a/plugins/automation/lib/discourse_automation/triggers/topic_tags_changed.rb b/plugins/automation/lib/discourse_automation/triggers/topic_tags_changed.rb
new file mode 100644
index 00000000000..d316573726f
--- /dev/null
+++ b/plugins/automation/lib/discourse_automation/triggers/topic_tags_changed.rb
@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+DiscourseAutomation::Triggerable.add(DiscourseAutomation::Triggers::TOPIC_TAGS_CHANGED) do
+  field :watching_categories, component: :categories
+  field :watching_tags, component: :tags
+end
diff --git a/plugins/automation/plugin.rb b/plugins/automation/plugin.rb
index 982d39c1dbd..2ec7249fbdb 100644
--- a/plugins/automation/plugin.rb
+++ b/plugins/automation/plugin.rb
@@ -72,6 +72,7 @@ after_initialize do
     lib/discourse_automation/triggers/recurring
     lib/discourse_automation/triggers/stalled_topic
     lib/discourse_automation/triggers/stalled_wiki
+    lib/discourse_automation/triggers/topic_tags_changed
     lib/discourse_automation/triggers/topic
     lib/discourse_automation/triggers/user_added_to_group
     lib/discourse_automation/triggers/user_badge_granted
@@ -181,6 +182,14 @@ after_initialize do
     DiscourseAutomation::EventHandlers.handle_pm_created(topic) if topic.private_message?
   end
 
+  on(:topic_tags_changed) do |topic, tags|
+    DiscourseAutomation::EventHandlers.handle_topic_tags_changed(
+      topic,
+      tags[:old_tag_names],
+      tags[:new_tag_names],
+    )
+  end
+
   on(:post_created) do |post|
     DiscourseAutomation::EventHandlers.handle_post_created_edited(post, :create)
   end
diff --git a/plugins/automation/spec/triggers/topic_tags_changed_spec.rb b/plugins/automation/spec/triggers/topic_tags_changed_spec.rb
new file mode 100644
index 00000000000..25e2c7190fe
--- /dev/null
+++ b/plugins/automation/spec/triggers/topic_tags_changed_spec.rb
@@ -0,0 +1,136 @@
+# frozen_string_literal: true
+
+describe DiscourseAutomation::Triggers::TOPIC_TAGS_CHANGED do
+  before { SiteSetting.discourse_automation_enabled = true }
+
+  fab!(:cool_tag) { Fabricate(:tag) }
+  fab!(:bad_tag) { Fabricate(:tag) }
+  fab!(:category)
+
+  fab!(:user)
+
+  fab!(:automation) do
+    Fabricate(:automation, trigger: DiscourseAutomation::Triggers::TOPIC_TAGS_CHANGED)
+  end
+
+  before do
+    SiteSetting.tagging_enabled = true
+    SiteSetting.create_tag_allowed_groups = Group::AUTO_GROUPS[:everyone]
+    SiteSetting.tag_topic_allowed_groups = Group::AUTO_GROUPS[:everyone]
+  end
+
+  context "when watching a cool tag" do
+    before do
+      automation.upsert_field!(
+        "watching_tags",
+        "tags",
+        { value: [cool_tag.name] },
+        target: "trigger",
+      )
+      automation.reload
+    end
+
+    it "should fire the trigger if the tag is added" do
+      topic_0 = Fabricate(:topic, user: user, tags: [], category: category)
+
+      list =
+        capture_contexts do
+          DiscourseTagging.tag_topic_by_names(topic_0, Guardian.new(user), [cool_tag.name])
+        end
+
+      expect(list.length).to eq(1)
+      expect(list[0]["kind"]).to eq(DiscourseAutomation::Triggers::TOPIC_TAGS_CHANGED)
+    end
+
+    it "should fire the trigger if the tag is removed" do
+      topic_0 = Fabricate(:topic, user: user, tags: [cool_tag], category: category)
+
+      list =
+        capture_contexts { DiscourseTagging.tag_topic_by_names(topic_0, Guardian.new(user), []) }
+
+      expect(list.length).to eq(1)
+      expect(list[0]["kind"]).to eq(DiscourseAutomation::Triggers::TOPIC_TAGS_CHANGED)
+    end
+
+    it "should not fire if the tag is not present" do
+      topic_0 = Fabricate(:topic, user: user, tags: [], category: category)
+
+      list =
+        capture_contexts do
+          DiscourseTagging.tag_topic_by_names(topic_0, Guardian.new(user), [bad_tag.name])
+        end
+
+      expect(list.length).to eq(0)
+    end
+  end
+
+  context "when watching a category" do
+    before do
+      automation.upsert_field!(
+        "watching_categories",
+        "categories",
+        { value: [category.id] },
+        target: "trigger",
+      )
+      automation.reload
+    end
+
+    it "should fire the trigger if the tag is added" do
+      topic_0 = Fabricate(:topic, user: user, tags: [], category: category)
+      topic_1 = Fabricate(:topic, user: user, tags: [], category: Fabricate(:category))
+
+      list =
+        capture_contexts do
+          DiscourseTagging.tag_topic_by_names(topic_0, Guardian.new(user), [bad_tag.name])
+          DiscourseTagging.tag_topic_by_names(topic_1, Guardian.new(user), [bad_tag.name])
+        end
+
+      expect(list.length).to eq(1)
+      expect(list[0]["kind"]).to eq(DiscourseAutomation::Triggers::TOPIC_TAGS_CHANGED)
+    end
+
+    it "should fire the trigger if the tag is removed" do
+      topic_0 = Fabricate(:topic, user: user, tags: [cool_tag], category: category)
+
+      list =
+        capture_contexts { DiscourseTagging.tag_topic_by_names(topic_0, Guardian.new(user), []) }
+      expect(list.length).to eq(1)
+      expect(list[0]["kind"]).to eq(DiscourseAutomation::Triggers::TOPIC_TAGS_CHANGED)
+    end
+
+    it "should not fire if not the watching category" do
+      topic_0 = Fabricate(:topic, user: user, tags: [], category: Fabricate(:category))
+
+      list =
+        capture_contexts do
+          DiscourseTagging.tag_topic_by_names(topic_0, Guardian.new(user), [cool_tag.name])
+        end
+
+      expect(list.length).to eq(0)
+    end
+  end
+
+  context "when without any watching tags or categories" do
+    it "should fire the trigger if the tag is added" do
+      topic_0 = Fabricate(:topic, user: user, tags: [], category: category)
+
+      list =
+        capture_contexts do
+          DiscourseTagging.tag_topic_by_names(topic_0, Guardian.new(user), [cool_tag.name])
+        end
+
+      expect(list.length).to eq(1)
+      expect(list[0]["kind"]).to eq(DiscourseAutomation::Triggers::TOPIC_TAGS_CHANGED)
+    end
+
+    it "should fire the trigger if the tag is removed" do
+      topic_0 = Fabricate(:topic, user: user, tags: [cool_tag], category: category)
+
+      list =
+        capture_contexts { DiscourseTagging.tag_topic_by_names(topic_0, Guardian.new(user), []) }
+
+      expect(list.length).to eq(1)
+      expect(list[0]["kind"]).to eq(DiscourseAutomation::Triggers::TOPIC_TAGS_CHANGED)
+    end
+  end
+end