diff --git a/app/commands/decidim/create_omniauth_registration.rb b/app/commands/decidim/create_omniauth_registration.rb
new file mode 100644
index 0000000..36a79b9
--- /dev/null
+++ b/app/commands/decidim/create_omniauth_registration.rb
@@ -0,0 +1,147 @@
+# frozen_string_literal: true
+
+module Decidim
+  # A command with all the business logic to create a user from omniauth
+  class CreateOmniauthRegistration < Decidim::Command
+    # Public: Initializes the command.
+    #
+    # form - A form object with the params.
+    def initialize(form, verified_email = nil)
+      @form = form
+      @verified_email = verified_email
+    end
+
+    # Executes the command. Broadcasts these events:
+    #
+    # - :ok when everything is valid.
+    # - :invalid if the form wasn't valid and we couldn't proceed.
+    #
+    # Returns nothing.
+    def call
+      verify_oauth_signature!
+
+      begin
+        if existing_identity
+          user = existing_identity.user
+          verify_user_confirmed(user)
+
+          return broadcast(:ok, user)
+        end
+        return broadcast(:invalid) if form.invalid?
+
+        transaction do
+          create_or_find_user
+          @identity = create_identity
+        end
+        trigger_omniauth_registration
+
+        broadcast(:ok, @user)
+      rescue ActiveRecord::RecordInvalid => e
+        broadcast(:error, e.record)
+      end
+    end
+
+    private
+
+    attr_reader :form, :verified_email
+
+    def create_or_find_user
+      generated_password = SecureRandom.hex
+
+      @user = User.find_or_initialize_by(
+        email: verified_email,
+        organization: organization
+      )
+
+      if @user.persisted?
+        # If user has left the account unconfirmed and later on decides to sign
+        # in with omniauth with an already verified account, the account needs
+        # to be marked confirmed.
+        @user.skip_confirmation! if !@user.confirmed? && @user.email == verified_email
+      else
+        @user.email = (verified_email || form.email)
+        @user.name = form.name
+        @user.nickname = form.normalized_nickname
+        @user.newsletter_notifications_at = nil
+        @user.password = generated_password
+        @user.password_confirmation = generated_password
+        if form.avatar_url.present?
+          url = URI.parse(form.avatar_url)
+          filename = File.basename(url.path)
+          file = url.open
+          @user.avatar.attach(io: file, filename: filename)
+        end
+        @user.extended_data = extended_data
+        @user.skip_confirmation! if verified_email
+      end
+
+      @user.tos_agreement = "1"
+      @user.save!
+    end
+
+    def create_identity
+      @user.identities.create!(
+        provider: form.provider,
+        uid: form.uid,
+        organization: organization
+      )
+    end
+
+    def organization
+      @form.current_organization
+    end
+
+    def existing_identity
+      @existing_identity ||= Identity.find_by(
+        user: organization.users,
+        provider: form.provider,
+        uid: form.uid
+      )
+    end
+
+    def verify_user_confirmed(user)
+      return true if user.confirmed?
+      return false if user.email != verified_email
+
+      user.skip_confirmation!
+      user.save!
+    end
+
+    def verify_oauth_signature!
+      raise InvalidOauthSignature, "Invalid oauth signature: #{form.oauth_signature}" unless signature_valid?
+    end
+
+    def signature_valid?
+      signature = OmniauthRegistrationForm.create_signature(form.provider, form.uid)
+      form.oauth_signature == signature
+    end
+
+    def trigger_omniauth_registration
+      ActiveSupport::Notifications.publish(
+        "decidim.user.omniauth_registration",
+        user_id: @user.id,
+        identity_id: @identity.id,
+        provider: form.provider,
+        uid: form.uid,
+        email: form.email,
+        name: form.name,
+        nickname: form.normalized_nickname,
+        avatar_url: form.avatar_url,
+        raw_data: form.raw_data
+      )
+    end
+
+    def extended_data
+      {
+        birth_date: form.birth_date,
+        address: form.address,
+        postal_code: form.postal_code,
+        city: form.city,
+        certification: form&.certification
+      }
+    end
+  end
+
+  class InvalidOauthSignature < StandardError
+  end
+end
diff --git a/app/views/decidim/devise/omniauth_registrations/new.html.erb b/app/views/decidim/devise/omniauth_registrations/new.html.erb
index 587e33e..764f58a 100644
--- a/app/views/decidim/devise/omniauth_registrations/new.html.erb
+++ b/app/views/decidim/devise/omniauth_registrations/new.html.erb
@@ -40,7 +40,7 @@
 
                   <div class="row">
                     <div class="columns medium-12">
-                      <%= f.date_select :birth_date, { label: t(".birth_date"), start_year: Date.today.year - 116, end_year: Date.today.year - 16 }, { class: "columns medium-3" } %>
+                      <%= f.date_select :birth_date, { label: t(".birth_date"), start_year: Date.today.year - 100, end_year: Date.today.year }, { class: "columns medium-3" } %>
                     </div>
                     <div class="columns margin-bottom-1">
                       <small><em><%= t(".birth_date_help") %></em></small>
@@ -63,6 +63,10 @@
                       </div>
                     </div>
                   </div>
+
+                  <div class="field">
+                    <%= f.check_box :certification, label: t(".certification") %>
+                  </div>
                 </div>
 
                 <%= f.hidden_field :email %>
diff --git a/lib/extends/forms/decidim/omniauth_registration_form_extend.rb b/lib/extends/forms/decidim/omniauth_registration_form_extend.rb
index 4800cd4..9939679 100644
--- a/lib/extends/forms/decidim/omniauth_registration_form_extend.rb
+++ b/lib/extends/forms/decidim/omniauth_registration_form_extend.rb
@@ -6,18 +6,22 @@ module OmniauthRegistrationFormExtend
   extend ActiveSupport::Concern
 
   included do
+    attribute :certification, ::ActiveModel::Type::Boolean
     attribute :birth_date, Date
     attribute :address, String
     attribute :postal_code, String
     attribute :city, String
 
-    validates :email, 'valid_email_2/email': { mx: true }
+    validates :email, "valid_email_2/email": { mx: true }
     validates :postal_code,
               :birth_date,
               :city,
               :address,
+              :certification,
               presence: true
 
+    validates :postal_code, numericality: { only_integer: true }, length: { is: 5 }
+    validates :certification, acceptance: true
     validate :over_16?
 
     private
@@ -34,4 +38,4 @@ def over_16?
 Decidim::OmniauthRegistrationForm.class_eval do
   clear_validators!
   include OmniauthRegistrationFormExtend
-end
\ No newline at end of file
+end