diff --git a/app/controllers/v1/activities_controller.rb b/app/controllers/v1/activities_controller.rb
index f9551525..b51904d5 100644
--- a/app/controllers/v1/activities_controller.rb
+++ b/app/controllers/v1/activities_controller.rb
@@ -18,13 +18,25 @@ def generate_alias
     render json: alias_response("#{mail_alias}@csvalpha.nl")
   end
 
-  def ical # rubocop:disable Metrics/AbcSize, Metrics/MethodLength
+  def ical # rubocop:disable Metrics/AbcSize, Metrics/MethodLength, Metrics/PerceivedComplexity, Metrics/CyclomaticComplexity
     return head :unauthorized unless authenticate_user_by_ical_secret_key
 
-    requested_categories = params[:categories].try(:split, ',')
+    stored_categories = @user.ical_categories
+
+    requested_categories = params[:categories]&.split(',')
+
+    permitted_categories = []
+
+    if stored_categories.empty? && requested_categories.present?
+      # this logic is only to store preferences on first use. this makes it so the end user doesn't notice the change
+      new_categories_to_store = requested_categories & Activity.categories
+      @user.update(ical_categories: new_categories_to_store)
+      permitted_categories = new_categories_to_store
+    else
+      permitted_categories = stored_categories & Activity.categories
+    end
+    permitted_categories = Activity.categories if permitted_categories.empty?
 
-    permitted_categories = (requested_categories & Activity.categories) ||
-                           Activity.categories
     activities_for_ical(permitted_categories).each do |act|
       calendar.add_event(act.to_ical)
     end
diff --git a/app/controllers/v1/users_controller.rb b/app/controllers/v1/users_controller.rb
index ac0e90e3..2f242e68 100644
--- a/app/controllers/v1/users_controller.rb
+++ b/app/controllers/v1/users_controller.rb
@@ -110,7 +110,7 @@ def context
   def excluded_display_properties
     %i[created_at updated_at deleted_at activated_at archived_at password_digest activation_token
        avatar activation_token_valid_till setup_complete otp_secret_key otp_required
-       ical_secret_key id]
+       ical_secret_key ical_categories id]
   end
 
   def otp_already_required_error
diff --git a/app/models/activity.rb b/app/models/activity.rb
index 6b3de661..083d59e2 100644
--- a/app/models/activity.rb
+++ b/app/models/activity.rb
@@ -34,8 +34,8 @@ class Activity < ApplicationRecord
   after_save :copy_author_and_group_to_form!
 
   def self.categories
-    %w[algemeen societeit vorming dinsdagkring woensdagkring
-       choose ifes ozon disputen kiemgroepen huizen extern eerstejaars curiositates]
+    %w[algemeen societeit vorming kring
+       choose ifes ozon disputen genootschapen huizen extern eerstejaars]
   end
 
   def full_day?
diff --git a/app/resources/v1/user_resource.rb b/app/resources/v1/user_resource.rb
index 5782f475..cc5dc867 100644
--- a/app/resources/v1/user_resource.rb
+++ b/app/resources/v1/user_resource.rb
@@ -4,7 +4,7 @@ class V1::UserResource < V1::ApplicationResource # rubocop:disable Metrics/Class
              :ifes_data_sharing_preference, :info_in_almanak, :almanak_subscription_preference,
              :digtus_subscription_preference, :email, :birthday, :address, :postcode, :city,
              :phone_number, :food_preferences, :vegetarian, :study, :start_study,
-             :picture_publication_preference, :ical_secret_key,
+             :picture_publication_preference, :ical_secret_key, :ical_categories,
              :password, :avatar, :avatar_url, :avatar_thumb_url,
              :user_details_sharing_preference, :allow_sofia_sharing, :trailer_drivers_license,
              :sidekiq_access, :setup_complete
@@ -51,7 +51,8 @@ def fetchable_fields
     # Relationships
     allowed_keys += %i[groups active_groups memberships mail_aliases mandates
                        group_mail_aliases permissions photos user_permissions]
-    allowed_keys += %i[ical_secret_key] if me?
+    # Ical fields
+    allowed_keys += %i[ical_secret_key ical_categories] if me?
     if update_or_me?
       allowed_keys += %i[login_enabled otp_required activated_at emergency_contact
                          emergency_number ifes_data_sharing_preference info_in_almanak
@@ -78,7 +79,8 @@ def self.creatable_fields(context) # rubocop:disable Metrics/MethodLength
       attributes += %i[otp_required password
                        user_details_sharing_preference allow_sofia_sharing
                        picture_publication_preference info_in_almanak
-                       ifes_data_sharing_preference sidekiq_access setup_complete]
+                       ifes_data_sharing_preference ical_categories sidekiq_access
+                       setup_complete]
     end
 
     if user_can_create_or_update?(context)
diff --git a/db/migrate/20251103104056_simplyfing_calender_options.rb b/db/migrate/20251103104056_simplyfing_calender_options.rb
new file mode 100644
index 00000000..4a5207ab
--- /dev/null
+++ b/db/migrate/20251103104056_simplyfing_calender_options.rb
@@ -0,0 +1,19 @@
+class SimplyfingCalenderOptions < ActiveRecord::Migration[7.2]
+  # rubocop:disable Rails/SkipsModelValidations
+  def up
+    add_column :users, :ical_categories, :string, array: true, default: []
+    Activity.where(category: 'dinsdagkring').update_all(category: 'kring')
+    Activity.where(category: 'woensdagkring').update_all(category: 'kring')
+    Activity.where(category: 'kiemgroepen').update_all(category: 'algemeen')
+    Activity.where(category: 'curiositates').update_all(category: 'algemeen')
+  end
+
+  def down
+    remove_column :users, :ical_categories
+    Activity.where(category: 'kring').update_all(category: 'dinsdagkring')
+    # NOTE: As mentioned before, reverting 'algemeen' to 'kiemgroepen' or 'curiositates'
+    # cannot be done reliably with `update_all` without additional information.
+    # The `down` migration here only addresses the 'kring' category.
+  end
+  # rubocop:enable Rails/SkipsModelValidations
+end
diff --git a/db/schema.rb b/db/schema.rb
index 20015070..1812a52a 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[7.1].define(version: 2025_03_10_235232) do
+ActiveRecord::Schema[7.1].define(version: 2025_11_03_104056) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
 
@@ -562,6 +562,7 @@
     t.string "nickname"
     t.boolean "trailer_drivers_license", default: false, null: false
     t.boolean "setup_complete", default: false, null: false
+    t.string "ical_categories", default: [], array: true
     t.index ["deleted_at"], name: "index_users_on_deleted_at"
     t.index ["email"], name: "index_users_on_email", unique: true
     t.index ["login_enabled"], name: "index_users_on_login_enabled"
diff --git a/spec/factories/activities.rb b/spec/factories/activities.rb
index 2d5a5df4..63692b97 100644
--- a/spec/factories/activities.rb
+++ b/spec/factories/activities.rb
@@ -10,8 +10,8 @@
     start_time { Faker::Time.between(from: 1.day.ago, to: Time.zone.today) }
     end_time { Faker::Time.between(from: 1.day.from_now, to: 2.days.from_now) }
     category do
-      %w[algemeen societeit vorming dinsdagkring woensdagkring
-         choose ifes ozon disputen kiemgroepen huizen extern eerstejaars curiositates].sample
+      %w[algemeen societeit vorming kring
+         choose ifes ozon disputen genootschapen huizen extern eerstejaars].sample
     end
     publicly_visible { false }
 
diff --git a/spec/models/activity_spec.rb b/spec/models/activity_spec.rb
index ff486844..e761f715 100644
--- a/spec/models/activity_spec.rb
+++ b/spec/models/activity_spec.rb
@@ -179,8 +179,8 @@
     context 'when it is another category' do
       let(:record) do
         build_stubbed(:activity,
-                      category: %w[algemeen sociëteit vorming dinsdagkring woensdagkring
-                                   disputen kiemgroepen huizen extern curiositates].sample)
+                      category: %w[algemeen sociëteit vorming kring
+                                   disputen genootschapen huizen extern].sample)
       end
 
       it { expect(record.humanized_category).to eq record.category.capitalize }
diff --git a/spec/resources/v1/user_resource_spec.rb b/spec/resources/v1/user_resource_spec.rb
index 2dd32966..3b3bb74b 100644
--- a/spec/resources/v1/user_resource_spec.rb
+++ b/spec/resources/v1/user_resource_spec.rb
@@ -99,7 +99,7 @@
       let(:another_user) { user }
       let(:fields) do
         basic_fields + update_fields +
-          read_fields + user_details_fields + %i[ical_secret_key]
+          read_fields + user_details_fields + %i[ical_secret_key ical_categories]
       end
 
       it { expect(resource.fetchable_fields).to match_array(fields) }
@@ -155,7 +155,7 @@
     context 'when record is current user' do
       let(:another_user) { user }
 
-      it { expect(creatable_fields).to match_array(basic_fields + current_user_fields) }
+      it { expect(creatable_fields).to match_array(basic_fields + current_user_fields + %i[ical_categories]) }
     end
 
     context 'when with create permisison' do
@@ -170,7 +170,7 @@
 
         it {
           expect(creatable_fields).to match_array(basic_fields + permissible_fields +
-                                                    current_user_fields - [:login_enabled])
+                                                    current_user_fields - [:login_enabled] + %i[ical_categories])
         }
       end
     end