diff --git a/app/controllers/sac_cas/event/participations_controller.rb b/app/controllers/sac_cas/event/participations_controller.rb
index 678d7ac78..953b07bb7 100644
--- a/app/controllers/sac_cas/event/participations_controller.rb
+++ b/app/controllers/sac_cas/event/participations_controller.rb
@@ -20,10 +20,10 @@ module SacCas::Event::ParticipationsController
     after_summon :enqueue_invoice_job
     after_assign :enqueue_confirmation_job # send_confirmation_email in core checks current_user_interested_in_mail? which should be irrelevant here
     before_cancel :assert_participant_cancelable?
-    after_cancel :cancel_invoices
   end
 
   def cancel
+    cancel_invoices
     entry.cancel_statement = params.dig(:event_participation, :cancel_statement)
     entry.canceled_at = params.dig(:event_participation, :canceled_at) || Time.zone.today
     entry.canceled_at = Time.zone.today if participant_cancels?
@@ -182,6 +182,6 @@ def cancel_invoices
       Invoices::Abacus::CancelInvoiceJob.new(invoice).enqueue!
     end
 
-    ExternalInvoice::CourseAnnulation.invoice!(entry)
+    ExternalInvoice::CourseAnnulation.invoice!(entry) unless entry.state == "applied"
   end
 end
diff --git a/spec/controllers/event/participations_controller_spec.rb b/spec/controllers/event/participations_controller_spec.rb
index cd49a4085..1c3bd915d 100644
--- a/spec/controllers/event/participations_controller_spec.rb
+++ b/spec/controllers/event/participations_controller_spec.rb
@@ -481,6 +481,15 @@
       expect(invoice.state).to eq("draft")
       expect(invoice.year).to eq(event.dates.first.start_at.year)
     end
+
+    it "PUT#cancel does not create course annulation invoice when participation state is applied" do
+      participation.update!(price: 10, price_category: :price_regular)
+      participation.update_column(:state, :applied)
+
+      expect do
+        put :cancel, params: params.merge({event_participation: {canceled_at: 1.day.ago}})
+      end.not_to change { ExternalInvoice::CourseAnnulation.count }
+    end
   end
 
   describe "PUT#update" do