diff --git a/app/assets/javascripts/new_design/champs/siret.js b/app/assets/javascripts/new_design/champs/siret.js
new file mode 100644
index 000000000..8904b05a6
--- /dev/null
+++ b/app/assets/javascripts/new_design/champs/siret.js
@@ -0,0 +1,27 @@
+document.addEventListener('turbolinks:load', function() {
+  $('[data-siret]').on('input', function(evt) {
+    var input = $(evt.target);
+    var value = input.val();
+    var url = input.attr('data-siret');
+    switch (value.length) {
+    case 0:
+      $.get(url+'?siret=blank');
+      break;
+    case 14:
+      input.attr('disabled', 'disabled');
+      $.get(url+'?siret='+value).then(function() {
+        input.removeAttr('data-invalid');
+        input.removeAttr('disabled');
+      }, function() {
+        input.removeAttr('disabled');
+        input.attr('data-invalid', true);
+      });
+      break;
+    default:
+      if (!input.attr('data-invalid')) {
+        input.attr('data-invalid', true);
+        $.get(url+'?siret=invalid');
+      }
+    }
+  });
+});
diff --git a/app/assets/stylesheets/new_design/forms.scss b/app/assets/stylesheets/new_design/forms.scss
index 17ef315f6..8c5191313 100644
--- a/app/assets/stylesheets/new_design/forms.scss
+++ b/app/assets/stylesheets/new_design/forms.scss
@@ -48,6 +48,10 @@
     .updated-at.highlighted {
       visibility: visible;
     }
+
+    .etablissement-titre {
+      margin-bottom: 2 * $default-padding;
+    }
   }
 
   .radios {
@@ -82,6 +86,10 @@
     &.small {
       padding: $default-padding / 2;
     }
+
+    &.small-margin {
+      margin-bottom: $default-padding / 2;
+    }
   }
 
   input[type=text],
diff --git a/app/controllers/champs/siret_controller.rb b/app/controllers/champs/siret_controller.rb
new file mode 100644
index 000000000..b1fb41b55
--- /dev/null
+++ b/app/controllers/champs/siret_controller.rb
@@ -0,0 +1,29 @@
+class Champs::SiretController < ApplicationController
+  def index
+    siret, champ_id = params.required([:siret, :champ_id])
+    @champ = Champs::SiretChamp.find(champ_id)
+    @etablissement = @champ.etablissement
+    if siret == 'blank'
+      if @etablissement
+        @etablissement.mark_for_destruction
+      end
+      @blank = true
+    elsif siret == 'invalid'
+      if @etablissement
+        @etablissement.mark_for_destruction
+      end
+      @error = "SIRET invalide"
+    else
+      etablissement_attributes = SIRETService.fetch(siret, @champ.dossier.procedure_id)
+      if etablissement_attributes.present?
+        @etablissement = @champ.build_etablissement(etablissement_attributes)
+        @etablissement.champ = @champ
+      else
+        @error = "SIRET invalide"
+      end
+    end
+    respond_to do |format|
+      format.js
+    end
+  end
+end
diff --git a/app/controllers/new_gestionnaire/dossiers_controller.rb b/app/controllers/new_gestionnaire/dossiers_controller.rb
index e978a348c..2cfb23257 100644
--- a/app/controllers/new_gestionnaire/dossiers_controller.rb
+++ b/app/controllers/new_gestionnaire/dossiers_controller.rb
@@ -198,7 +198,10 @@ module NewGestionnaire
     end
 
     def champs_private_params
-      params.require(:dossier).permit(champs_private_attributes: [:id, :piece_justificative_file, :value, value: []])
+      params.require(:dossier).permit(champs_private_attributes: [
+        :id, :piece_justificative_file, :value, value: [],
+        etablissement_attributes: Champs::SiretChamp::ETABLISSEMENT_ATTRIBUTES
+      ])
     end
 
     def check_attestation_emailable
diff --git a/app/controllers/new_user/dossiers_controller.rb b/app/controllers/new_user/dossiers_controller.rb
index b4501c8e6..b0a63fb8a 100644
--- a/app/controllers/new_user/dossiers_controller.rb
+++ b/app/controllers/new_user/dossiers_controller.rb
@@ -116,7 +116,12 @@ module NewUser
 
     # FIXME: require(:dossier) when all the champs are united
     def champs_params
-      params.permit(dossier: { champs_attributes: [:id, :value, :piece_justificative_file, value: []] })
+      params.permit(dossier: {
+        champs_attributes: [
+          :id, :value, :piece_justificative_file, value: [],
+          etablissement_attributes: Champs::SiretChamp::ETABLISSEMENT_ATTRIBUTES
+        ]
+      })
     end
 
     def dossier
diff --git a/app/helpers/type_de_champ_helper.rb b/app/helpers/type_de_champ_helper.rb
index f91158bf6..12bb3674a 100644
--- a/app/helpers/type_de_champ_helper.rb
+++ b/app/helpers/type_de_champ_helper.rb
@@ -6,6 +6,10 @@ module TypeDeChampHelper
       tdcs.reject! { |tdc| tdc.last == "piece_justificative" }
     end
 
+    if !current_administrateur.feature_enabled?(:champ_siret_allowed)
+      tdcs.reject! { |tdc| tdc.last == "siret" }
+    end
+
     tdcs
   end
 end
diff --git a/app/models/champs/siret_champ.rb b/app/models/champs/siret_champ.rb
index 91e237032..0a55edb32 100644
--- a/app/models/champs/siret_champ.rb
+++ b/app/models/champs/siret_champ.rb
@@ -1,4 +1,42 @@
 class Champs::SiretChamp < Champ
+  ETABLISSEMENT_ATTRIBUTES = [
+    :id,
+    :_destroy,
+    :signature,
+    :siret,
+    :siege_social,
+    :naf,
+    :libelle_naf,
+    :adresse,
+    :numero_voie,
+    :type_voie,
+    :nom_voie,
+    :code_postal,
+    :localite,
+    :code_insee_localite,
+    :entreprise_siren,
+    :entreprise_capital_social,
+    :entreprise_numero_tva_intracommunautaire,
+    :entreprise_forme_juridique,
+    :entreprise_forme_juridique_code,
+    :entreprise_nom_commercial,
+    :entreprise_raison_sociale,
+    :entreprise_siret_siege_social,
+    :entreprise_code_effectif_entreprise,
+    :entreprise_date_creation,
+    :entreprise_nom,
+    :entreprise_prenom,
+    :association_rna,
+    :association_titre,
+    :association_objet,
+    :association_date_creation,
+    :association_date_declaration,
+    :association_date_publication,
+    exercices_attributes: [
+      [:id, :ca, :date_fin_exercice, :date_fin_exercice_timestamp]
+    ]
+  ]
+
   belongs_to :etablissement, dependent: :destroy
   accepts_nested_attributes_for :etablissement, allow_destroy: true, update_only: true
 end
diff --git a/app/models/etablissement.rb b/app/models/etablissement.rb
index af9c0a2a4..840e1aed5 100644
--- a/app/models/etablissement.rb
+++ b/app/models/etablissement.rb
@@ -8,7 +8,10 @@ class Etablissement < ApplicationRecord
   accepts_nested_attributes_for :exercices
   accepts_nested_attributes_for :entreprise, update_only: true
 
-  validates :dossier_id, uniqueness: true
+  validates :siret, presence: true
+  validates :dossier_id, uniqueness: { allow_nil: true }
+
+  validate :validate_signature
 
   def geo_adresse
     [numero_voie, type_voie, nom_voie, complement_adresse, code_postal, localite].join(' ')
@@ -18,6 +21,11 @@ class Etablissement < ApplicationRecord
     # squeeze needed because of space in excess in the data
     "#{numero_voie} #{type_voie} #{nom_voie}, #{complement_adresse}, #{code_postal} #{localite}".squeeze(' ')
   end
+
+  def titre
+    entreprise_raison_sociale || association_titre
+  end
+
   def verify
     SignatureService.verify(signature, message_for_signature)
   end
@@ -28,6 +36,14 @@ class Etablissement < ApplicationRecord
 
   attr_accessor :signature
 
+  private
+
+  def validate_signature
+    if champ && !verify
+      errors.add(:base, 'Numéro SIRET introuvable.')
+    end
+  end
+
   def message_for_signature
     JSON.pretty_generate(as_json(include: {
       exercices: { only: [:ca, :date_fin_exercice, :date_fin_exercice_timestamp] }
diff --git a/app/models/type_de_champ.rb b/app/models/type_de_champ.rb
index a10e445a7..ca90df71c 100644
--- a/app/models/type_de_champ.rb
+++ b/app/models/type_de_champ.rb
@@ -20,7 +20,8 @@ class TypeDeChamp < ApplicationRecord
     header_section: 'header_section',
     explication: 'explication',
     dossier_link: 'dossier_link',
-    piece_justificative: 'piece_justificative'
+    piece_justificative: 'piece_justificative',
+    siret: 'siret'
   }
 
   belongs_to :procedure
diff --git a/app/views/champs/siret/index.js.erb b/app/views/champs/siret/index.js.erb
new file mode 100644
index 000000000..899f52440
--- /dev/null
+++ b/app/views/champs/siret/index.js.erb
@@ -0,0 +1,8 @@
+(function() {
+  <% if @blank || @error %>
+    var html = "<%= escape_javascript(render partial: 'shared/champs/siret/delete_etablissement', locals: { message: @error, position: @champ.order_place, etablissement: @etablissement }) %>";
+  <% else %>
+    var html = "<%= escape_javascript(render partial: 'shared/champs/siret/etablissement', locals: { position: @champ.order_place, etablissement: @etablissement }) %>";
+  <% end %>
+  $("#etablissement-for-<%= @champ.id %>").html(html);
+})();
diff --git a/app/views/shared/champs/siret/_delete_etablissement.html.haml b/app/views/shared/champs/siret/_delete_etablissement.html.haml
new file mode 100644
index 000000000..279c69c2c
--- /dev/null
+++ b/app/views/shared/champs/siret/_delete_etablissement.html.haml
@@ -0,0 +1,6 @@
+= message
+- if etablissement.present?
+  - champ_attributes = etablissement.champ.private? ? 'champs_private_attributes' : 'champs_attributes'
+  = fields_for "dossier[#{champ_attributes}][#{position}][etablissement_attributes]", etablissement do |form|
+    = form.hidden_field :_destroy
+
diff --git a/app/views/shared/champs/siret/_etablissement.html.haml b/app/views/shared/champs/siret/_etablissement.html.haml
new file mode 100644
index 000000000..893a5ef2a
--- /dev/null
+++ b/app/views/shared/champs/siret/_etablissement.html.haml
@@ -0,0 +1,4 @@
+= render partial: 'shared/dossiers/editable_champs/etablissement_titre', locals: { etablissement: etablissement }
+- champ_attributes = etablissement.champ.private? ? 'champs_private_attributes' : 'champs_attributes'
+= fields_for "dossier[#{champ_attributes}][#{position}][etablissement_attributes]", etablissement do |form|
+  = render partial: 'shared/dossiers/editable_champs/etablissement', locals: { form: form, signature: etablissement.sign }
diff --git a/app/views/shared/dossiers/editable_champs/_etablissement.html.haml b/app/views/shared/dossiers/editable_champs/_etablissement.html.haml
new file mode 100644
index 000000000..81d5baac9
--- /dev/null
+++ b/app/views/shared/dossiers/editable_champs/_etablissement.html.haml
@@ -0,0 +1,34 @@
+= form.hidden_field :signature, value: signature
+= form.hidden_field :siret
+= form.hidden_field :siege_social
+= form.hidden_field :naf
+= form.hidden_field :libelle_naf
+= form.hidden_field :adresse
+= form.hidden_field :numero_voie
+= form.hidden_field :type_voie
+= form.hidden_field :nom_voie
+= form.hidden_field :code_postal
+= form.hidden_field :localite
+= form.hidden_field :code_insee_localite
+= form.hidden_field :entreprise_siren
+= form.hidden_field :entreprise_capital_social
+= form.hidden_field :entreprise_numero_tva_intracommunautaire
+= form.hidden_field :entreprise_forme_juridique
+= form.hidden_field :entreprise_forme_juridique_code
+= form.hidden_field :entreprise_nom_commercial
+= form.hidden_field :entreprise_raison_sociale
+= form.hidden_field :entreprise_siret_siege_social
+= form.hidden_field :entreprise_code_effectif_entreprise
+= form.hidden_field :entreprise_date_creation
+= form.hidden_field :entreprise_nom
+= form.hidden_field :entreprise_prenom
+= form.hidden_field :association_rna
+= form.hidden_field :association_titre
+= form.hidden_field :association_objet
+= form.hidden_field :association_date_creation
+= form.hidden_field :association_date_declaration
+= form.hidden_field :association_date_publication
+= form.fields_for :exercices do |form|
+  = form.hidden_field :ca
+  = form.hidden_field :date_fin_exercice
+  = form.hidden_field :date_fin_exercice_timestamp
diff --git a/app/views/shared/dossiers/editable_champs/_etablissement_titre.html.haml b/app/views/shared/dossiers/editable_champs/_etablissement_titre.html.haml
new file mode 100644
index 000000000..b63734321
--- /dev/null
+++ b/app/views/shared/dossiers/editable_champs/_etablissement_titre.html.haml
@@ -0,0 +1,6 @@
+.etablissement-titre
+  = etablissement.titre
+  = etablissement.entreprise_forme_juridique
+  - if etablissement.entreprise_capital_social.present?
+    au capital social de
+    = number_to_currency(etablissement.entreprise_capital_social)
diff --git a/app/views/shared/dossiers/editable_champs/_siret.html.haml b/app/views/shared/dossiers/editable_champs/_siret.html.haml
new file mode 100644
index 000000000..2135b274f
--- /dev/null
+++ b/app/views/shared/dossiers/editable_champs/_siret.html.haml
@@ -0,0 +1,10 @@
+= form.text_field :value,
+  placeholder: champ.libelle,
+  class: 'small-margin',
+  data: { siret: champs_siret_path(format: :js, champ_id: champ) },
+  required: champ.mandatory?
+%div{ id: "etablissement-for-#{champ.id}" }
+  - if champ.etablissement.present?
+    = render partial: 'shared/dossiers/editable_champs/etablissement_titre', locals: { etablissement: champ.etablissement }
+  = form.fields_for :etablissement do |form|
+    = render partial: 'shared/dossiers/editable_champs/etablissement', locals: { form: form, signature: champ.etablissement.sign }
diff --git a/config/initializers/features.yml b/config/initializers/features.yml
index b0210bbe9..a7b150256 100644
--- a/config/initializers/features.yml
+++ b/config/initializers/features.yml
@@ -2,3 +2,5 @@ remote_storage: false
 weekly_overview: false
 champ_pj_allowed_for_admin_ids:
   - 0
+champ_siret_allowed_for_admin_ids:
+  - 0
diff --git a/config/routes.rb b/config/routes.rb
index b2cb6bea7..901dd75cb 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -72,6 +72,10 @@ Rails.application.routes.draw do
     get 'particulier/callback' => 'particulier#callback'
   end
 
+  namespace :champs do
+    get ':champ_id/siret' => 'siret#index', as: 'siret'
+  end
+
   namespace :users do
     namespace :dossiers do
       resources :invites, only: [:index, :show]
diff --git a/spec/controllers/new_user/dossiers_controller_spec.rb b/spec/controllers/new_user/dossiers_controller_spec.rb
index 0b4645124..af8dfd898 100644
--- a/spec/controllers/new_user/dossiers_controller_spec.rb
+++ b/spec/controllers/new_user/dossiers_controller_spec.rb
@@ -235,7 +235,7 @@ describe NewUser::DossiersController, type: :controller do
 
     context 'when the update fails' do
       before do
-        expect_any_instance_of(Dossier).to receive(:update).and_return(false)
+        expect_any_instance_of(Dossier).to receive(:save).and_return(false)
         expect_any_instance_of(Dossier).to receive(:errors)
           .and_return(double(full_messages: ['nop']))