diff --git a/app/controllers/users/dossiers_controller.rb b/app/controllers/users/dossiers_controller.rb
index 987939cc6..67c67335c 100644
--- a/app/controllers/users/dossiers_controller.rb
+++ b/app/controllers/users/dossiers_controller.rb
@@ -161,7 +161,8 @@ module Users
     end
 
     def extend_conservation
-      dossier.update(en_construction_conservation_extension: dossier.en_construction_conservation_extension + 1.month)
+      dossier.update(en_construction_conservation_extension: dossier.en_construction_conservation_extension + 1.month,
+        conservation_extension: dossier.en_construction_conservation_extension + 1.month)
       flash[:notice] = 'Votre dossier sera conservé un mois supplémentaire'
       redirect_to dossier_path(@dossier)
     end
diff --git a/app/models/dossier.rb b/app/models/dossier.rb
index 08dd41243..a448a41c4 100644
--- a/app/models/dossier.rb
+++ b/app/models/dossier.rb
@@ -7,6 +7,7 @@
 #  archived                                           :boolean          default(FALSE)
 #  autorisation_donnees                               :boolean
 #  brouillon_close_to_expiration_notice_sent_at       :datetime
+#  conservation_extension                             :interval         default(0 seconds)
 #  deleted_user_email_never_send                      :string
 #  en_construction_at                                 :datetime
 #  en_construction_close_to_expiration_notice_sent_at :datetime
@@ -636,6 +637,7 @@ class Dossier < ApplicationRecord
   end
 
   def after_passer_en_construction
+    update!(conservation_extension: 0.days)
     update!(en_construction_at: Time.zone.now) if self.en_construction_at.nil?
   end
 
@@ -652,6 +654,7 @@ class Dossier < ApplicationRecord
   end
 
   def after_repasser_en_construction(instructeur)
+    update!(conservation_extension: 0.days)
     log_dossier_operation(instructeur, :repasser_en_construction)
   end
 
diff --git a/db/migrate/20210428104228_add_conservation_extension_to_dossiers.rb b/db/migrate/20210428104228_add_conservation_extension_to_dossiers.rb
new file mode 100644
index 000000000..8b72f17ca
--- /dev/null
+++ b/db/migrate/20210428104228_add_conservation_extension_to_dossiers.rb
@@ -0,0 +1,5 @@
+class AddConservationExtensionToDossiers < ActiveRecord::Migration[6.1]
+  def change
+    add_column :dossiers, :conservation_extension, :interval
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index ccf0e6e28..911ebb453 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: 2021_05_04_115445) do
+ActiveRecord::Schema.define(version: 2021_05_05_115445) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -274,6 +274,7 @@ ActiveRecord::Schema.define(version: 2021_05_04_115445) do
     t.datetime "last_avis_updated_at"
     t.datetime "last_commentaire_updated_at"
     t.string "api_entreprise_job_exceptions", array: true
+    t.interval "conservation_extension"
     t.string "deleted_user_email_never_send"
     t.index "to_tsvector('french'::regconfig, (search_terms || private_search_terms))", name: "index_dossiers_on_search_terms_private_search_terms", using: :gin
     t.index "to_tsvector('french'::regconfig, search_terms)", name: "index_dossiers_on_search_terms", using: :gin
diff --git a/lib/tasks/deployment/20210429172327_rename_conservation_extension.rake b/lib/tasks/deployment/20210429172327_rename_conservation_extension.rake
new file mode 100644
index 000000000..070fbfeff
--- /dev/null
+++ b/lib/tasks/deployment/20210429172327_rename_conservation_extension.rake
@@ -0,0 +1,24 @@
+namespace :after_party do
+  desc 'Deployment task: rename_conservation_extension'
+  task rename_conservation_extension: :environment do
+    puts "Running deploy task 'rename_conservation_extension'"
+
+    BATCH_SIZE = 20000
+
+    dossiers = Dossier.state_en_construction.where.not(en_construction_conservation_extension: 0.days)
+    dossiers.find_each do |dossier|
+      dossier.update_column(:conservation_extension, dossier.en_construction_conservation_extension)
+    end
+
+    dossiers = Dossier.where(conservation_extension: nil)
+    n = (dossiers.count / BATCH_SIZE).ceil + 1
+    n.times do
+      dossiers.limit(BATCH_SIZE).update_all(conservation_extension: 0.days)
+    end
+
+    # Update task as completed.  If you remove the line below, the task will
+    # run with every deploy (or every time you call after_party:run).
+    AfterParty::TaskRecord
+      .create version: AfterParty::TaskRecorder.new(__FILE__).timestamp
+  end
+end