diff --git a/app/controllers/champs/champ_controller.rb b/app/controllers/champs/champ_controller.rb
index 73ecb3044..adf03a778 100644
--- a/app/controllers/champs/champ_controller.rb
+++ b/app/controllers/champs/champ_controller.rb
@@ -7,7 +7,7 @@ class Champs::ChampController < ApplicationController
   def find_champ
     dossier = policy_scope(Dossier).includes(:champs, revision: [:types_de_champ]).find(params[:dossier_id])
     type_de_champ = dossier.find_type_de_champ_by_stable_id(params[:stable_id])
-    dossier.champ_for_update(type_de_champ, params_row_id)
+    dossier.champ_for_update(type_de_champ, params_row_id, updated_by: current_user.email)
   end
 
   def params_row_id
diff --git a/app/controllers/instructeurs/dossiers_controller.rb b/app/controllers/instructeurs/dossiers_controller.rb
index 7657f9a48..3fa84c917 100644
--- a/app/controllers/instructeurs/dossiers_controller.rb
+++ b/app/controllers/instructeurs/dossiers_controller.rb
@@ -274,7 +274,7 @@ module Instructeurs
     end
 
     def update_annotations
-      dossier_with_champs.update_champs_attributes(champs_private_attributes_params, :private)
+      dossier_with_champs.update_champs_attributes(champs_private_attributes_params, :private, updated_by: current_user.email)
       if dossier.champs.any?(&:changed_for_autosave?)
         dossier.last_champ_private_updated_at = Time.zone.now
       end
diff --git a/app/controllers/users/dossiers_controller.rb b/app/controllers/users/dossiers_controller.rb
index 592f16f2c..acdfd1332 100644
--- a/app/controllers/users/dossiers_controller.rb
+++ b/app/controllers/users/dossiers_controller.rb
@@ -551,7 +551,7 @@ module Users
     end
 
     def update_dossier_and_compute_errors
-      @dossier.update_champs_attributes(champs_public_attributes_params, :public)
+      @dossier.update_champs_attributes(champs_public_attributes_params, :public, updated_by: current_user.email)
       if @dossier.champs.any?(&:changed_for_autosave?)
         @dossier.last_champ_updated_at = Time.zone.now
       end
diff --git a/app/graphql/mutations/dossier_modifier_annotation.rb b/app/graphql/mutations/dossier_modifier_annotation.rb
index 30dbd6f7e..de467fa00 100644
--- a/app/graphql/mutations/dossier_modifier_annotation.rb
+++ b/app/graphql/mutations/dossier_modifier_annotation.rb
@@ -44,7 +44,7 @@ module Mutations
         .find_by(type_champ: annotation_type_champ, stable_id:)
 
       return nil if type_de_champ.nil?
-      dossier.champ_for_update(type_de_champ, row_id)
+      dossier.champ_for_update(type_de_champ, row_id, updated_by: current_administrateur.email)
     end
 
     def annotation_type_champ
diff --git a/app/models/concerns/dossier_champs_concern.rb b/app/models/concerns/dossier_champs_concern.rb
index 40c0692c8..a5c05a5d0 100644
--- a/app/models/concerns/dossier_champs_concern.rb
+++ b/app/models/concerns/dossier_champs_concern.rb
@@ -55,18 +55,18 @@ module DossierChampsConcern
       .types_de_champ
       .filter { _1.stable_id.in?(stable_ids) }
       .filter { !revision.child?(_1) }
-      .map { champ_for_update(_1, nil) }
+      .map { champ_for_update(_1, nil, updated_by: nil) }
   end
 
-  def champ_for_update(type_de_champ, row_id)
-    champ, attributes = champ_with_attributes_for_update(type_de_champ, row_id)
+  def champ_for_update(type_de_champ, row_id, updated_by:)
+    champ, attributes = champ_with_attributes_for_update(type_de_champ, row_id, updated_by:)
     champ.assign_attributes(attributes)
     champ
   end
 
-  def update_champs_attributes(attributes, scope)
+  def update_champs_attributes(attributes, scope, updated_by:)
     champs_attributes = attributes.to_h.map do |public_id, attributes|
-      champ_attributes_by_public_id(public_id, attributes, scope)
+      champ_attributes_by_public_id(public_id, attributes, scope, updated_by:)
     end
 
     assign_attributes(champs_attributes:)
@@ -87,13 +87,13 @@ module DossierChampsConcern
     end
   end
 
-  def champ_attributes_by_public_id(public_id, attributes, scope)
+  def champ_attributes_by_public_id(public_id, attributes, scope, updated_by:)
     stable_id, row_id = public_id.split('-')
     type_de_champ = find_type_de_champ_by_stable_id(stable_id, scope)
-    champ_with_attributes_for_update(type_de_champ, row_id).last.merge(attributes)
+    champ_with_attributes_for_update(type_de_champ, row_id, updated_by:).last.merge(attributes)
   end
 
-  def champ_with_attributes_for_update(type_de_champ, row_id)
+  def champ_with_attributes_for_update(type_de_champ, row_id, updated_by:)
     attributes = type_de_champ.params_for_champ
     # TODO: Once we have the right index in place, we should change this to use `create_or_find_by` instead of `find_or_create_by`
     champ = champs
@@ -101,6 +101,7 @@ module DossierChampsConcern
       .find_or_create_by!(stable_id: type_de_champ.stable_id, row_id:)
 
     attributes[:id] = champ.id
+    attributes[:updated_by] = updated_by
 
     # Needed when a revision change the champ type in this case, we reset the champ data
     if champ.type != attributes[:type]
diff --git a/app/models/types_de_champ/prefill_repetition_type_de_champ.rb b/app/models/types_de_champ/prefill_repetition_type_de_champ.rb
index e90457e4b..a61e7119d 100644
--- a/app/models/types_de_champ/prefill_repetition_type_de_champ.rb
+++ b/app/models/types_de_champ/prefill_repetition_type_de_champ.rb
@@ -64,7 +64,7 @@ class TypesDeChamp::PrefillRepetitionTypeDeChamp < TypesDeChamp::PrefillTypeDeCh
         type_de_champ = revision.types_de_champ.find { _1.stable_id == stable_id }
         next unless type_de_champ
 
-        subchamp = champ.dossier.champ_for_update(type_de_champ, row_id)
+        subchamp = champ.dossier.champ_for_update(type_de_champ, row_id, updated_by: nil)
         TypesDeChamp::PrefillTypeDeChamp.build(subchamp.type_de_champ, revision).to_assignable_attributes(subchamp, value)
       end.compact
     end
diff --git a/db/migrate/20240513140508_add_updated_by_to_champs.rb b/db/migrate/20240513140508_add_updated_by_to_champs.rb
new file mode 100644
index 000000000..d7621ab6b
--- /dev/null
+++ b/db/migrate/20240513140508_add_updated_by_to_champs.rb
@@ -0,0 +1,5 @@
+class AddUpdatedByToChamps < ActiveRecord::Migration[7.0]
+  def change
+    add_column :champs, :updated_by, :text
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 74b41f6c7..6f7fcfe7c 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -263,6 +263,7 @@ ActiveRecord::Schema[7.0].define(version: 2024_05_27_090508) do
     t.string "type"
     t.integer "type_de_champ_id"
     t.datetime "updated_at", precision: nil
+    t.text "updated_by"
     t.string "value"
     t.jsonb "value_json"
     t.index ["dossier_id"], name: "index_champs_on_dossier_id"
diff --git a/spec/controllers/champs/piece_justificative_controller_spec.rb b/spec/controllers/champs/piece_justificative_controller_spec.rb
index 0c0eba1e1..d63c4b77a 100644
--- a/spec/controllers/champs/piece_justificative_controller_spec.rb
+++ b/spec/controllers/champs/piece_justificative_controller_spec.rb
@@ -10,7 +10,6 @@ describe Champs::PieceJustificativeController, type: :controller do
 
     subject do
       put :update, params: {
-        position: '1',
         dossier_id: champ.dossier_id,
         stable_id: champ.stable_id,
         blob_signed_id: file
@@ -49,7 +48,7 @@ describe Champs::PieceJustificativeController, type: :controller do
       # See https://github.com/betagouv/demarches-simplifiees.fr/issues/4926
       before do
         champ
-        expect_any_instance_of(Champs::PieceJustificativeChamp).to receive(:save).twice.and_return(false)
+        expect_any_instance_of(Champs::PieceJustificativeChamp).to receive(:save).and_return(false)
         expect_any_instance_of(Champs::PieceJustificativeChamp).to receive(:errors)
           .and_return(double(full_messages: ['La pièce justificative n’est pas d’un type accepté']))
       end
diff --git a/spec/models/concerns/dossier_champs_concern_spec.rb b/spec/models/concerns/dossier_champs_concern_spec.rb
index a9e58ca77..42d22a340 100644
--- a/spec/models/concerns/dossier_champs_concern_spec.rb
+++ b/spec/models/concerns/dossier_champs_concern_spec.rb
@@ -124,7 +124,7 @@ RSpec.describe DossierChampsConcern do
     let(:row_id) { nil }
 
     context "public champ" do
-      subject { dossier.champ_for_update(type_de_champ_public, row_id) }
+      subject { dossier.champ_for_update(type_de_champ_public, row_id, updated_by: dossier.user.email) }
 
       it {
         expect(subject.persisted?).to be_truthy
@@ -165,7 +165,7 @@ RSpec.describe DossierChampsConcern do
     end
 
     context "private champ" do
-      subject { dossier.champ_for_update(type_de_champ_private, row_id) }
+      subject { dossier.champ_for_update(type_de_champ_private, row_id, updated_by: dossier.user.email) }
 
       it {
         expect(subject.persisted?).to be_truthy
@@ -191,7 +191,7 @@ RSpec.describe DossierChampsConcern do
     let(:champ_991) { dossier.project_champ(dossier.find_type_de_champ_by_stable_id(991), nil) }
     let(:champ_994) { dossier.project_champ(dossier.find_type_de_champ_by_stable_id(994), row_id) }
 
-    subject { dossier.update_champs_attributes(attributes, :public) }
+    subject { dossier.update_champs_attributes(attributes, :public, updated_by: dossier.user.email) }
 
     it {
       subject
@@ -229,7 +229,7 @@ RSpec.describe DossierChampsConcern do
 
     let(:annotation_995) { dossier.project_champ(dossier.find_type_de_champ_by_stable_id(995), nil) }
 
-    subject { dossier.update_champs_attributes(attributes, :private) }
+    subject { dossier.update_champs_attributes(attributes, :private, updated_by: dossier.user.email) }
 
     it {
       subject