diff --git a/app/serializers/basic_group_serializer.rb b/app/serializers/basic_group_serializer.rb
index 3fee36fcba5..e51e6000022 100644
--- a/app/serializers/basic_group_serializer.rb
+++ b/app/serializers/basic_group_serializer.rb
@@ -9,7 +9,6 @@ class BasicGroupSerializer < ApplicationSerializer
              :mentionable_level,
              :messageable_level,
              :visibility_level,
-             :automatic_membership_email_domains,
              :primary_group,
              :title,
              :grant_trust_level,
@@ -34,50 +33,6 @@ class BasicGroupSerializer < ApplicationSerializer
              :can_admin_group,
              :publish_read_state
 
-  def self.admin_attributes(*attrs)
-    attributes(*attrs)
-    attrs.each do |attr|
-      define_method "include_#{attr}?" do
-        scope.is_admin?
-      end
-    end
-  end
-
-  admin_attributes :automatic_membership_email_domains,
-                   :smtp_server,
-                   :smtp_port,
-                   :smtp_ssl,
-                   :imap_server,
-                   :imap_port,
-                   :imap_ssl,
-                   :imap_mailbox_name,
-                   :imap_mailboxes,
-                   :email_username,
-                   :email_password,
-                   :imap_last_error,
-                   :imap_old_emails,
-                   :imap_new_emails
-
-  def self.admin_or_owner_attributes(*attrs)
-    attributes(*attrs)
-    attrs.each do |attr|
-      define_method "include_#{attr}?" do
-        scope.is_admin? || (include_is_group_owner? && is_group_owner)
-      end
-    end
-  end
-
-  admin_or_owner_attributes :watching_category_ids,
-                            :tracking_category_ids,
-                            :watching_first_post_category_ids,
-                            :regular_category_ids,
-                            :muted_category_ids,
-                            :watching_tags,
-                            :watching_first_post_tags,
-                            :tracking_tags,
-                            :regular_tags,
-                            :muted_tags
-
   def include_display_name?
     object.automatic
   end
@@ -132,16 +87,6 @@ class BasicGroupSerializer < ApplicationSerializer
     scope.can_see_group_members?(object)
   end
 
-  [:watching, :regular, :tracking, :watching_first_post, :muted].each do |level|
-    define_method("#{level}_category_ids") do
-      GroupCategoryNotificationDefault.lookup(object, level).pluck(:category_id)
-    end
-
-    define_method("#{level}_tags") do
-      GroupTagNotificationDefault.lookup(object, level).joins(:tag).pluck('tags.name')
-    end
-  end
-
   private
 
   def staff?
diff --git a/app/serializers/group_show_serializer.rb b/app/serializers/group_show_serializer.rb
index 29a81c645aa..ee54b335849 100644
--- a/app/serializers/group_show_serializer.rb
+++ b/app/serializers/group_show_serializer.rb
@@ -3,6 +3,50 @@
 class GroupShowSerializer < BasicGroupSerializer
   attributes :is_group_user, :is_group_owner, :is_group_owner_display, :mentionable, :messageable, :flair_icon, :flair_type
 
+  def self.admin_attributes(*attrs)
+    attributes(*attrs)
+    attrs.each do |attr|
+      define_method "include_#{attr}?" do
+        scope.is_admin?
+      end
+    end
+  end
+
+  admin_attributes :automatic_membership_email_domains,
+                   :smtp_server,
+                   :smtp_port,
+                   :smtp_ssl,
+                   :imap_server,
+                   :imap_port,
+                   :imap_ssl,
+                   :imap_mailbox_name,
+                   :imap_mailboxes,
+                   :email_username,
+                   :email_password,
+                   :imap_last_error,
+                   :imap_old_emails,
+                   :imap_new_emails
+
+  def self.admin_or_owner_attributes(*attrs)
+    attributes(*attrs)
+    attrs.each do |attr|
+      define_method "include_#{attr}?" do
+        scope.is_admin? || (include_is_group_owner? && is_group_owner)
+      end
+    end
+  end
+
+  admin_or_owner_attributes :watching_category_ids,
+                            :tracking_category_ids,
+                            :watching_first_post_category_ids,
+                            :regular_category_ids,
+                            :muted_category_ids,
+                            :watching_tags,
+                            :watching_first_post_tags,
+                            :tracking_tags,
+                            :regular_tags,
+                            :muted_tags
+
   def include_is_group_user?
     authenticated?
   end
@@ -51,6 +95,16 @@ class GroupShowSerializer < BasicGroupSerializer
     flair_type.present? && (is_group_owner || scope.is_admin?)
   end
 
+  [:watching, :regular, :tracking, :watching_first_post, :muted].each do |level|
+    define_method("#{level}_category_ids") do
+      group_category_notifications[NotificationLevels.all[level]] || []
+    end
+
+    define_method("#{level}_tags") do
+      group_tag_notifications[NotificationLevels.all[level]] || []
+    end
+  end
+
   private
 
   def authenticated?
@@ -61,4 +115,27 @@ class GroupShowSerializer < BasicGroupSerializer
     return @group_user if defined?(@group_user)
     @group_user = object.group_users.find_by(user: scope.user)
   end
+
+  def group_category_notifications
+    @group_category_notification_defaults ||=
+      GroupCategoryNotificationDefault.where(group_id: object.id)
+        .pluck(:notification_level, :category_id)
+        .inject({}) do |h, arr|
+          h[arr[0]] ||= []
+          h[arr[0]] << arr[1]
+          h
+        end
+  end
+
+  def group_tag_notifications
+    @group_tag_notification_defaults ||=
+      GroupTagNotificationDefault.where(group_id: object.id)
+        .joins(:tag)
+        .pluck(:notification_level, :name)
+        .inject({}) do |h, arr|
+          h[arr[0]] ||= []
+          h[arr[0]] << arr[1]
+          h
+        end
+  end
 end
diff --git a/spec/serializers/basic_group_serializer_spec.rb b/spec/serializers/basic_group_serializer_spec.rb
index 4000751696c..799d106f126 100644
--- a/spec/serializers/basic_group_serializer_spec.rb
+++ b/spec/serializers/basic_group_serializer_spec.rb
@@ -40,22 +40,6 @@ describe BasicGroupSerializer do
     end
   end
 
-  describe '#automatic_membership_email_domains' do
-    fab!(:group) { Fabricate(:group, automatic_membership_email_domains: 'ilovediscourse.com') }
-    let(:admin_guardian) { Guardian.new(Fabricate(:admin)) }
-
-    it 'should include email domains for admin' do
-      subject = described_class.new(group, scope: admin_guardian, root: false, owner_group_ids: [group.id])
-      expect(subject.as_json[:automatic_membership_email_domains]).to eq('ilovediscourse.com')
-    end
-
-    it 'should not include email domains for other users' do
-      subject = described_class.new(group, scope: guardian, root: false, owner_group_ids: [group.id])
-      expect(subject.as_json[:automatic_membership_email_domains]).to eq(nil)
-    end
-
-  end
-
   describe '#has_messages' do
     fab!(:group) { Fabricate(:group, has_messages: true) }
 
@@ -113,26 +97,4 @@ describe BasicGroupSerializer do
       end
     end
   end
-
-  describe 'admin only fields' do
-    fab!(:group) { Fabricate(:group, email_username: 'foo@bar.com', email_password: 'pa$$w0rd') }
-
-    describe 'for a user' do
-      let(:guardian) { Guardian.new(Fabricate(:user)) }
-
-      it 'are not visible' do
-        expect(subject.as_json[:email_username]).to be_nil
-        expect(subject.as_json[:email_password]).to be_nil
-      end
-    end
-
-    describe 'for an admin' do
-      let(:guardian) { Guardian.new(Fabricate(:admin)) }
-
-      it 'are visible' do
-        expect(subject.as_json[:email_username]).to eq('foo@bar.com')
-        expect(subject.as_json[:email_password]).to eq('pa$$w0rd')
-      end
-    end
-  end
 end
diff --git a/spec/serializers/group_show_serializer_spec.rb b/spec/serializers/group_show_serializer_spec.rb
index 6d1c0bcfab8..597e0bf7a90 100644
--- a/spec/serializers/group_show_serializer_spec.rb
+++ b/spec/serializers/group_show_serializer_spec.rb
@@ -44,4 +44,100 @@ describe GroupShowSerializer do
       expect(json[:group_show][:mentionable]).to eq(true)
     end
   end
+
+  describe '#automatic_membership_email_domains' do
+    fab!(:group) { Fabricate(:group, automatic_membership_email_domains: 'ilovediscourse.com') }
+    let(:admin_guardian) { Guardian.new(Fabricate(:admin)) }
+
+    it 'should include email domains for admin' do
+      subject = described_class.new(group, scope: admin_guardian, root: false, owner_group_ids: [group.id])
+      expect(subject.as_json[:automatic_membership_email_domains]).to eq('ilovediscourse.com')
+    end
+
+    it 'should not include email domains for other users' do
+      subject = described_class.new(group, scope: Guardian.new, root: false, owner_group_ids: [group.id])
+      expect(subject.as_json[:automatic_membership_email_domains]).to eq(nil)
+    end
+  end
+
+  describe 'admin only fields' do
+    fab!(:group) { Fabricate(:group, email_username: 'foo@bar.com', email_password: 'pa$$w0rd') }
+    subject { described_class.new(group, scope: guardian, root: false) }
+
+    describe 'for a user' do
+      let(:guardian) { Guardian.new(Fabricate(:user)) }
+
+      it 'are not visible' do
+        expect(subject.as_json[:email_username]).to be_nil
+        expect(subject.as_json[:email_password]).to be_nil
+      end
+    end
+
+    describe 'for an admin' do
+      let(:guardian) { Guardian.new(Fabricate(:admin)) }
+
+      it 'are visible' do
+        expect(subject.as_json[:email_username]).to eq('foo@bar.com')
+        expect(subject.as_json[:email_password]).to eq('pa$$w0rd')
+      end
+    end
+  end
+
+  describe "default notification settings" do
+    subject { described_class.new(group, scope: guardian, root: false) }
+    let(:category1) { Fabricate(:category) }
+    let(:category2) { Fabricate(:category) }
+    let(:tag1) { Fabricate(:tag) }
+    let(:tag2) { Fabricate(:tag) }
+
+    before do
+      GroupCategoryNotificationDefault.create!(
+        group: group,
+        category: category1,
+        notification_level: GroupCategoryNotificationDefault.notification_levels[:watching]
+      )
+      GroupCategoryNotificationDefault.create!(
+        group: group,
+        category: category2,
+        notification_level: GroupCategoryNotificationDefault.notification_levels[:tracking]
+      )
+      GroupTagNotificationDefault.create!(
+        group: group,
+        tag: tag1,
+        notification_level: GroupTagNotificationDefault.notification_levels[:watching]
+      )
+      GroupTagNotificationDefault.create!(
+        group: group,
+        tag: tag2,
+        notification_level: GroupTagNotificationDefault.notification_levels[:tracking]
+      )
+    end
+
+    describe "for a user" do
+      let(:guardian) { Guardian.new(Fabricate(:user)) }
+
+      it "are not visible" do
+        expect(subject.as_json.keys.select { |k| k.to_s.ends_with?("_category_ids") }).to be_empty
+        expect(subject.as_json.keys.select { |k| k.to_s.ends_with?("_tags") }).to be_empty
+      end
+    end
+
+    describe "for admin" do
+      let(:guardian) { Guardian.new(Fabricate(:admin)) }
+
+      it "are correct" do
+        expect(subject.as_json[:watching_category_ids]).to eq([category1.id])
+        expect(subject.as_json[:tracking_category_ids]).to eq([category2.id])
+        expect(subject.as_json[:watching_first_post_category_ids]).to eq([])
+        expect(subject.as_json[:regular_category_ids]).to eq([])
+        expect(subject.as_json[:muted_category_ids]).to eq([])
+
+        expect(subject.as_json[:watching_tags]).to eq([tag1.name])
+        expect(subject.as_json[:tracking_tags]).to eq([tag2.name])
+        expect(subject.as_json[:watching_first_post_tags]).to eq([])
+        expect(subject.as_json[:regular_tags]).to eq([])
+        expect(subject.as_json[:muted_tags]).to eq([])
+      end
+    end
+  end
 end