diff --git a/app/jobs/prepare_base_notifications_job.rb b/app/jobs/prepare_base_notifications_job.rb
index cdee85a06..d0a1da324 100644
--- a/app/jobs/prepare_base_notifications_job.rb
+++ b/app/jobs/prepare_base_notifications_job.rb
@@ -52,10 +52,17 @@ def subscriptions(move, action_name:, only_supplier_id: nil)
   end
 
   def build_and_send_notifications(subscription, type_id, topic, action_name, queue_as)
+    type = event_type(action_name, topic, type_id, subscription)
+
+    if type.starts_with?('cross_supplier_')
+      enabled_suppliers = ENV.fetch('FEATURE_FLAG_CROSS_DECK_NOTIFICATIONS_SUPPLIERS', '').split(',')
+      return unless enabled_suppliers.include?(subscription.supplier.key)
+    end
+
     notification = subscription.notifications.create!(
       notification_type_id: type_id,
       topic:,
-      event_type: event_type(action_name, topic, type_id, subscription),
+      event_type: type,
     )
     notify_job(type_id).perform_later(notification_id: notification.id, queue_as:)
   end
diff --git a/helm_deploy/values-staging.yaml b/helm_deploy/values-staging.yaml
index 2ef55076d..3a2ad78a3 100644
--- a/helm_deploy/values-staging.yaml
+++ b/helm_deploy/values-staging.yaml
@@ -19,7 +19,7 @@ generic-service:
     SENTRY_ENVIRONMENT: "staging"
     SERVER_FQDN: "hmpps-book-secure-move-api-staging.apps.cloud-platform.service.justice.gov.uk"
     WEB_CONCURRENCY: "3"
-
+    FEATURE_FLAG_CROSS_DECK_NOTIFICATIONS_SUPPLIERS: "geoamey,serco"
 
   # Pre-existing kubernetes secrets to load as environment variables in the deployment.
   # namespace_secrets:
diff --git a/helm_deploy/values-uat.yaml b/helm_deploy/values-uat.yaml
index 54964d857..3424f5001 100644
--- a/helm_deploy/values-uat.yaml
+++ b/helm_deploy/values-uat.yaml
@@ -18,7 +18,6 @@ generic-service:
     SENTRY_ENVIRONMENT: "uat"
     SERVER_FQDN: "hmpps-book-secure-move-api-uat.apps.cloud-platform.service.justice.gov.uk"
 
-
   # Pre-existing kubernetes secrets to load as environment variables in the deployment.
   # namespace_secrets:
   #   [name of kubernetes secret]:
diff --git a/spec/jobs/prepare_move_notifications_job_spec.rb b/spec/jobs/prepare_move_notifications_job_spec.rb
index 97772b0a3..a5113374d 100644
--- a/spec/jobs/prepare_move_notifications_job_spec.rb
+++ b/spec/jobs/prepare_move_notifications_job_spec.rb
@@ -15,6 +15,7 @@
   let(:send_webhooks) { true }
   let(:send_emails) { true }
   let(:only_supplier_id) { nil }
+  let(:envs) { { FEATURE_FLAG_CROSS_DECK_NOTIFICATIONS_SUPPLIERS: 'geoamey,serco' } }
 
   before do
     create(:notification_type, :webhook)
@@ -24,6 +25,12 @@
     allow(NotifyEmailJob).to receive(:perform_later)
   end
 
+  around do |example|
+    ClimateControl.modify(**envs) do
+      example.run
+    end
+  end
+
   shared_examples_for 'it creates a webhook notification record' do
     it do
       expect { perform }.to change(Notification.webhooks, :count).by(1)
@@ -99,8 +106,8 @@
     end
 
     context 'when it is a cross-deck move' do
-      let!(:initial_supplier) { create(:supplier) }
-      let!(:receiving_supplier) { create(:supplier) }
+      let!(:initial_supplier) { create(:supplier, :serco) }
+      let!(:receiving_supplier) { create(:supplier, :geoamey) }
       let!(:subscription) { create(:subscription, :no_email_address, supplier: initial_supplier) }
       let!(:subscription2) { create(:subscription, :no_email_address, supplier: receiving_supplier) }
       let(:to_location) { create :location, :court, suppliers: [receiving_supplier] }
@@ -113,6 +120,17 @@
           [subscription2.id, 'cross_supplier_move_add'],
         )
       end
+
+      context 'when the feature flag is not set' do
+        let(:envs) { { FEATURE_FLAG_CROSS_DECK_NOTIFICATIONS_SUPPLIERS: '' } }
+
+        it 'only sends the create_move notification to the initial supplier' do
+          perform
+          expect(Notification.webhooks.order(:created_at).pluck(:subscription_id, :event_type)).to contain_exactly(
+            [subscription.id, 'create_move'],
+          )
+        end
+      end
     end
   end
 
@@ -145,8 +163,8 @@
     end
 
     context 'when it is updated to become a cross-deck move' do
-      let!(:initial_supplier) { create(:supplier) }
-      let!(:receiving_supplier) { create(:supplier) }
+      let!(:initial_supplier) { create(:supplier, :serco) }
+      let!(:receiving_supplier) { create(:supplier, :geoamey) }
       let!(:subscription) { create(:subscription, :no_email_address, supplier: initial_supplier) }
       let!(:subscription2) { create(:subscription, :no_email_address, supplier: receiving_supplier) }
       let(:to_location) { create :location, :court, suppliers: [receiving_supplier] }
@@ -159,11 +177,22 @@
           [subscription2.id, 'cross_supplier_move_add'],
         )
       end
+
+      context 'when the feature flag is not set' do
+        let(:envs) { { FEATURE_FLAG_CROSS_DECK_NOTIFICATIONS_SUPPLIERS: '' } }
+
+        it 'only sends the update_move notification to the initial supplier' do
+          perform
+          expect(Notification.webhooks.order(:created_at).pluck(:subscription_id, :event_type)).to contain_exactly(
+            [subscription.id, 'update_move'],
+          )
+        end
+      end
     end
 
     context 'when it is a cross-deck move that has already been notified' do
-      let!(:initial_supplier) { create(:supplier) }
-      let!(:receiving_supplier) { create(:supplier) }
+      let!(:initial_supplier) { create(:supplier, :serco) }
+      let!(:receiving_supplier) { create(:supplier, :geoamey) }
       let!(:subscription) { create(:subscription, :no_email_address, supplier: initial_supplier) }
       let!(:subscription2) { create(:subscription, :no_email_address, supplier: receiving_supplier) }
       let(:to_location) { create :location, :court, suppliers: [receiving_supplier] }
@@ -172,11 +201,26 @@
 
       it 'sends the update_move and cross_supplier_move_update notifications to the suppliers' do
         perform
-        expect(Notification.webhooks.order(:created_at).last(2).pluck(:subscription_id, :event_type)).to contain_exactly(
+        expect(
+          Notification.webhooks.order(:created_at).where.not(event_type: 'cross_supplier_move_add').pluck(:subscription_id, :event_type),
+        ).to contain_exactly(
           [subscription.id, 'update_move'],
           [subscription2.id, 'cross_supplier_move_update'],
         )
       end
+
+      context 'when the feature flag is not set' do
+        let(:envs) { { FEATURE_FLAG_CROSS_DECK_NOTIFICATIONS_SUPPLIERS: '' } }
+
+        it 'only sends the update_move notification to the initial supplier' do
+          perform
+          expect(
+            Notification.webhooks.order(:created_at).where.not(event_type: 'cross_supplier_move_add').pluck(:subscription_id, :event_type),
+          ).to contain_exactly(
+            [subscription.id, 'update_move'],
+          )
+        end
+      end
     end
   end
 
@@ -242,8 +286,8 @@
 
   context 'when explicitly notifying a cross-deck move' do
     let(:action_name) { 'cross_supplier_add' }
-    let!(:initial_supplier) { create(:supplier) }
-    let!(:receiving_supplier) { create(:supplier) }
+    let!(:initial_supplier) { create(:supplier, :serco) }
+    let!(:receiving_supplier) { create(:supplier, :geoamey) }
     let!(:subscription) { create(:subscription, :no_email_address, supplier: initial_supplier) }
     let!(:subscription2) { create(:subscription, :no_email_address, supplier: receiving_supplier) }
     let(:to_location) { create :location, :court, suppliers: [receiving_supplier] }
@@ -255,12 +299,21 @@
         [subscription2.id, 'cross_supplier_move_add'],
       )
     end
+
+    context 'when the feature flag is not set' do
+      let(:envs) { { FEATURE_FLAG_CROSS_DECK_NOTIFICATIONS_SUPPLIERS: '' } }
+
+      it 'does not notify the receiving supplier' do
+        perform
+        expect(Notification.webhooks.order(:created_at).pluck(:subscription_id, :event_type)).to be_empty
+      end
+    end
   end
 
   context 'when explicitly notifying that a move is no longer cross-deck' do
     let(:action_name) { 'cross_supplier_remove' }
-    let!(:initial_supplier) { create(:supplier) }
-    let!(:receiving_supplier) { create(:supplier) }
+    let!(:initial_supplier) { create(:supplier, :serco) }
+    let!(:receiving_supplier) { create(:supplier, :geoamey) }
     let!(:subscription) { create(:subscription, :no_email_address, supplier: initial_supplier) }
     let!(:subscription2) { create(:subscription, :no_email_address, supplier: receiving_supplier) }
     let(:to_location) { create :location, :court, suppliers: [receiving_supplier] }
@@ -272,6 +325,15 @@
       expect(Notification.webhooks.where.not(event_type: 'cross_supplier_move_add').pluck(:subscription_id, :event_type))
         .to contain_exactly([subscription2.id, 'cross_supplier_move_remove'])
     end
+
+    context 'when the feature flag is not set' do
+      let(:envs) { { FEATURE_FLAG_CROSS_DECK_NOTIFICATIONS_SUPPLIERS: '' } }
+
+      it 'does not notify the receiving supplier' do
+        perform
+        expect(Notification.webhooks.where.not(event_type: 'cross_supplier_move_add').pluck(:subscription_id, :event_type)).to be_empty
+      end
+    end
   end
 
   context 'when confirming a person escort record' do
diff --git a/spec/requests/api/allocations_controller_update_spec.rb b/spec/requests/api/allocations_controller_update_spec.rb
index 32758fe75..3fe807906 100644
--- a/spec/requests/api/allocations_controller_update_spec.rb
+++ b/spec/requests/api/allocations_controller_update_spec.rb
@@ -13,6 +13,14 @@
     resource
   end
 
+  let(:envs) { { FEATURE_FLAG_CROSS_DECK_NOTIFICATIONS_SUPPLIERS: 'geoamey,serco' } }
+
+  around do |example|
+    ClimateControl.modify(**envs) do
+      example.run
+    end
+  end
+
   describe 'PATCH /allocations' do
     subject(:patch_allocations) do
       patch "/api/allocations/#{allocation.id}", params: { data: }, headers:, as: :json
@@ -25,7 +33,7 @@
     let(:headers) { { 'Authorization' => "Bearer #{access_token}", 'CONTENT_TYPE': content_type } }
     let(:existing_date) { Date.new(2023, 1, 1) }
     let(:new_date) { existing_date.tomorrow }
-    let(:supplier) { create(:supplier) }
+    let(:supplier) { create(:supplier, :serco) }
     let!(:allocation) { create(:allocation, date: existing_date, moves_count:) }
     let!(:moves) { create_list(:move, moves_count, allocation:, date: existing_date, person: create(:person), supplier:) }
 
diff --git a/spec/requests/api/moves_controller_create_v2_spec.rb b/spec/requests/api/moves_controller_create_v2_spec.rb
index edbd7ba07..e8f125798 100644
--- a/spec/requests/api/moves_controller_create_v2_spec.rb
+++ b/spec/requests/api/moves_controller_create_v2_spec.rb
@@ -7,7 +7,7 @@
 
   let(:response_json) { JSON.parse(response.body) }
   let(:schema) { load_yaml_schema('post_moves_responses.yaml', version: 'v2') }
-  let(:supplier) { create(:supplier) }
+  let(:supplier) { create(:supplier, :serco) }
   let(:access_token) { 'spoofed-token' }
   let(:content_type) { ApiController::CONTENT_TYPE }
 
@@ -25,6 +25,14 @@
     }
   end
 
+  let(:envs) { { FEATURE_FLAG_CROSS_DECK_NOTIFICATIONS_SUPPLIERS: 'geoamey,serco' } }
+
+  around do |example|
+    ClimateControl.modify(**envs) do
+      example.run
+    end
+  end
+
   describe 'POST /moves' do
     let(:move_attributes) do
       {
@@ -737,7 +745,7 @@
         allow(Faraday).to receive(:new).and_return(faraday_client)
       end
 
-      let!(:receiving_supplier) { create(:supplier) }
+      let!(:receiving_supplier) { create(:supplier, :geoamey) }
       let!(:subscription) { create(:subscription, :no_email_address, supplier: another_supplier) }
       let!(:subscription2) { create(:subscription, :no_email_address, supplier: receiving_supplier) }
       let(:to_location) { create :location, :court, suppliers: [receiving_supplier] }
diff --git a/spec/requests/api/moves_controller_update_v2_spec.rb b/spec/requests/api/moves_controller_update_v2_spec.rb
index cfbc73d99..362238364 100644
--- a/spec/requests/api/moves_controller_update_v2_spec.rb
+++ b/spec/requests/api/moves_controller_update_v2_spec.rb
@@ -9,7 +9,7 @@
   let(:response_json) { JSON.parse(response.body) }
   let(:schema) { load_yaml_schema('patch_move_responses.yaml', version: 'v2') }
   let(:access_token) { 'spoofed-token' }
-  let(:supplier) { create(:supplier) }
+  let(:supplier) { create(:supplier, :serco) }
 
   let(:resource_to_json) do
     JSON.parse(V2::MoveSerializer.new(move.reload, serializer: V2::MoveSerializer).serializable_hash.to_json)
@@ -24,6 +24,14 @@
     }
   end
 
+  let(:envs) { { FEATURE_FLAG_CROSS_DECK_NOTIFICATIONS_SUPPLIERS: 'geoamey,serco' } }
+
+  around do |example|
+    ClimateControl.modify(**envs) do
+      example.run
+    end
+  end
+
   describe 'PATCH /moves' do
     let!(:move) { create :move, :proposed, :prison_recall, from_location:, profile:, supplier: }
 
@@ -341,7 +349,7 @@
     end
 
     context 'when it is a cross-deck move' do
-      let!(:receiving_supplier) { create(:supplier) }
+      let!(:receiving_supplier) { create(:supplier, :geoamey) }
       let!(:subscription) { create(:subscription, :no_email_address, supplier:) }
       let!(:subscription2) { create(:subscription, :no_email_address, supplier: receiving_supplier) }
       let(:to_location) { create :location, :court, suppliers: [receiving_supplier] }