diff --git a/app/models/assign_to.rb b/app/models/assign_to.rb
index 8febd4b3c..4343b3375 100644
--- a/app/models/assign_to.rb
+++ b/app/models/assign_to.rb
@@ -6,7 +6,7 @@
 #  daily_email_notifications_enabled               :boolean          default(FALSE), not null
 #  instant_email_dossier_notifications_enabled     :boolean          default(FALSE), not null
 #  instant_email_message_notifications_enabled     :boolean          default(FALSE), not null
-#  instant_expert_avis_email_notifications_enabled :boolean          default(FALSE), not null
+#  instant_expert_avis_email_notifications_enabled :boolean          default(FALSE)
 #  manager                                         :boolean          default(FALSE)
 #  weekly_email_notifications_enabled              :boolean          default(TRUE), not null
 #  created_at                                      :datetime
diff --git a/db/migrate/20220830125703_add_avis_email_notification.rb b/db/migrate/20220830125703_add_avis_email_notification.rb
index 9bf4e9a16..7604b8394 100644
--- a/db/migrate/20220830125703_add_avis_email_notification.rb
+++ b/db/migrate/20220830125703_add_avis_email_notification.rb
@@ -1,5 +1,10 @@
 class AddAvisEmailNotification < ActiveRecord::Migration[6.1]
-  def change
-    add_column :assign_tos, :instant_expert_avis_email_notifications_enabled, :boolean, default: false, null: false
+  def up
+    add_column :assign_tos, :instant_expert_avis_email_notifications_enabled, :boolean
+    change_column_default :assign_tos, :instant_expert_avis_email_notifications_enabled, false
+  end
+
+  def down
+    remove_column :assign_tos, :instant_expert_avis_email_notifications_enabled
   end
 end
diff --git a/db/migrate/20220902151143_backfill_add_avis_email_notification.rb b/db/migrate/20220902151143_backfill_add_avis_email_notification.rb
new file mode 100644
index 000000000..19a7396b2
--- /dev/null
+++ b/db/migrate/20220902151143_backfill_add_avis_email_notification.rb
@@ -0,0 +1,10 @@
+class BackfillAddAvisEmailNotification < ActiveRecord::Migration[6.1]
+  def up
+    AssignTo.in_batches do |relation|
+      relation.update_all instant_expert_avis_email_notifications_enabled: false
+      sleep(0.01)
+    end
+
+    add_check_constraint :assign_tos, "instant_expert_avis_email_notifications_enabled IS NOT NULL", name: "assign_tos_instant_expert_avis_email_notifications_enabled_null", validate: false
+  end
+end
diff --git a/db/migrate/20220902151920_validate_backfill_add_avis_email_notification.rb b/db/migrate/20220902151920_validate_backfill_add_avis_email_notification.rb
new file mode 100644
index 000000000..a0433dcfe
--- /dev/null
+++ b/db/migrate/20220902151920_validate_backfill_add_avis_email_notification.rb
@@ -0,0 +1,5 @@
+class ValidateBackfillAddAvisEmailNotification < ActiveRecord::Migration[6.1]
+  def change
+    validate_check_constraint :assign_tos, name: "assign_tos_instant_expert_avis_email_notifications_enabled_null"
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 31a4c228b..361097d7d 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.define(version: 2022_08_30_125703) do
+ActiveRecord::Schema.define(version: 2022_09_02_151920) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "pgcrypto"
@@ -111,7 +111,7 @@ ActiveRecord::Schema.define(version: 2022_08_30_125703) do
     t.bigint "groupe_instructeur_id"
     t.boolean "instant_email_dossier_notifications_enabled", default: false, null: false
     t.boolean "instant_email_message_notifications_enabled", default: false, null: false
-    t.boolean "instant_expert_avis_email_notifications_enabled", default: false, null: false
+    t.boolean "instant_expert_avis_email_notifications_enabled", default: false
     t.integer "instructeur_id"
     t.boolean "manager", default: false
     t.datetime "updated_at"
@@ -119,6 +119,7 @@ ActiveRecord::Schema.define(version: 2022_08_30_125703) do
     t.index ["groupe_instructeur_id", "instructeur_id"], name: "unique_couple_groupe_instructeur_instructeur", unique: true
     t.index ["groupe_instructeur_id"], name: "index_assign_tos_on_groupe_instructeur_id"
     t.index ["instructeur_id"], name: "index_assign_tos_on_instructeur_id"
+    t.check_constraint "instant_expert_avis_email_notifications_enabled IS NOT NULL", name: "assign_tos_instant_expert_avis_email_notifications_enabled_null"
   end
 
   create_table "attestation_templates", id: :serial, force: :cascade do |t|