diff --git a/app/controllers/categories_controller.rb b/app/controllers/categories_controller.rb
index 2931dbc42ec..4e7337eaf0d 100644
--- a/app/controllers/categories_controller.rb
+++ b/app/controllers/categories_controller.rb
@@ -26,7 +26,8 @@ class CategoriesController < ApplicationController
     category_options = {
       is_homepage: current_homepage == "categories",
       parent_category_id: params[:parent_category_id],
-      include_topics: include_topics(parent_category)
+      include_topics: include_topics(parent_category),
+      include_subcategories: params[:include_subcategories] == "true"
     }
 
     @category_list = CategoryList.new(guardian, category_options)
diff --git a/app/models/category.rb b/app/models/category.rb
index 07b890e0644..630a74c425a 100644
--- a/app/models/category.rb
+++ b/app/models/category.rb
@@ -139,7 +139,7 @@ class Category < ActiveRecord::Base
 
   # permission is just used by serialization
   # we may consider wrapping this in another spot
-  attr_accessor :displayable_topics, :permission, :subcategory_ids, :notification_level, :has_children
+  attr_accessor :displayable_topics, :permission, :subcategory_ids, :subcategory_list, :notification_level, :has_children
 
   # Allows us to skip creating the category definition topic in tests.
   attr_accessor :skip_category_definition
diff --git a/app/models/category_list.rb b/app/models/category_list.rb
index 4144f79b423..655edfa194e 100644
--- a/app/models/category_list.rb
+++ b/app/models/category_list.rb
@@ -100,6 +100,8 @@ class CategoryList
 
     @categories = @categories.to_a
 
+    include_subcategories = @options[:include_subcategories] == true
+
     notification_levels = CategoryUser.notification_levels_for(@guardian.user)
     default_notification_level = CategoryUser.default_notification_level
 
@@ -111,16 +113,26 @@ class CategoryList
     end
 
     if @options[:parent_category_id].blank?
-      subcategories = {}
+      subcategory_ids = {}
+      subcategory_list = {}
       to_delete = Set.new
       @categories.each do |c|
         if c.parent_category_id.present?
-          subcategories[c.parent_category_id] ||= []
-          subcategories[c.parent_category_id] << c.id
+          subcategory_ids[c.parent_category_id] ||= []
+          subcategory_ids[c.parent_category_id] << c.id
+          if include_subcategories
+            subcategory_list[c.parent_category_id] ||= []
+            subcategory_list[c.parent_category_id] << c
+          end
           to_delete << c
         end
       end
-      @categories.each { |c| c.subcategory_ids = subcategories[c.id] || [] }
+      @categories.each do |c|
+        c.subcategory_ids = subcategory_ids[c.id] || []
+        if include_subcategories
+          c.subcategory_list = subcategory_list[c.id] || []
+        end
+      end
       @categories.delete_if { |c| to_delete.include?(c) }
     end
 
diff --git a/app/serializers/category_detailed_serializer.rb b/app/serializers/category_detailed_serializer.rb
index 6b1e5083b20..1349cd44aa8 100644
--- a/app/serializers/category_detailed_serializer.rb
+++ b/app/serializers/category_detailed_serializer.rb
@@ -14,10 +14,16 @@ class CategoryDetailedSerializer < BasicCategorySerializer
 
   has_many :displayable_topics, serializer: ListableTopicSerializer, embed: :objects, key: :topics
 
+  has_many :subcategory_list, serializer: CategoryDetailedSerializer, embed: :objects, key: :subcategory_list
+
   def include_displayable_topics?
     displayable_topics.present?
   end
 
+  def include_subcategory_list?
+    subcategory_list.present?
+  end
+
   def is_uncategorized
     object.id == SiteSetting.uncategorized_category_id
   end
diff --git a/spec/requests/api/schemas/json/category_list_response.json b/spec/requests/api/schemas/json/category_list_response.json
index 1aa3c8f0648..fc3c424a4b4 100644
--- a/spec/requests/api/schemas/json/category_list_response.json
+++ b/spec/requests/api/schemas/json/category_list_response.json
@@ -141,6 +141,15 @@
 
                   ]
                 },
+                "subcategory_list": {
+                  "type": [
+                    "array",
+                    "null"
+                  ],
+                  "items": [
+
+                  ]
+                },
                 "uploaded_logo": {
                   "type": [
                     "string",
diff --git a/spec/requests/categories_controller_spec.rb b/spec/requests/categories_controller_spec.rb
index 2cfed06d614..2067279cf13 100644
--- a/spec/requests/categories_controller_spec.rb
+++ b/spec/requests/categories_controller_spec.rb
@@ -68,6 +68,55 @@ describe CategoriesController do
       )
     end
 
+    it 'does not returns subcatgories without permission' do
+      subcategory = Fabricate(:category,  user: admin, parent_category: category)
+      subcategory.set_permissions(admins: :full)
+      subcategory.save!
+
+      sign_in(user)
+
+      get "/categories.json?include_subcategories=true"
+
+      expect(response.status).to eq(200)
+
+      category_list = response.parsed_body["category_list"]
+
+      subcategories_for_category = category_list["categories"][1]["subcategory_list"]
+      expect(subcategories_for_category).to eq(nil)
+    end
+
+    it 'returns the right subcategory response with permission' do
+      subcategory = Fabricate(:category, user: admin, parent_category: category)
+
+      sign_in(user)
+
+      get "/categories.json?include_subcategories=true"
+
+      expect(response.status).to eq(200)
+
+      category_list = response.parsed_body["category_list"]
+
+      subcategories_for_category = category_list["categories"][1]["subcategory_list"]
+      expect(subcategories_for_category.count).to eq(1)
+      expect(subcategories_for_category.first["parent_category_id"]).to eq(category.id)
+      expect(subcategories_for_category.first["id"]).to eq(subcategory.id)
+    end
+
+    it 'does not return subcategories without query param' do
+      subcategory = Fabricate(:category, user: admin, parent_category: category)
+
+      sign_in(user)
+
+      get "/categories.json"
+
+      expect(response.status).to eq(200)
+
+      category_list = response.parsed_body["category_list"]
+
+      subcategories_for_category = category_list["categories"][1]["subcategory_list"]
+      expect(subcategories_for_category).to eq(nil)
+    end
+
     it 'does not show uncategorized unless allow_uncategorized_topics' do
       SiteSetting.desktop_category_page_style = "categories_boxes_with_topics"