diff --git a/lib/infin/companies.ex b/lib/infin/companies.ex
index 4fcccbb..66e9cea 100644
--- a/lib/infin/companies.ex
+++ b/lib/infin/companies.ex
@@ -55,7 +55,10 @@ defmodule Infin.Companies do
   """
   def get_company_by_nif!(nif), do: Repo.get_by!(Company, nif: nif)
 
-  def get_company_by_nif(nif), do: Repo.get_by(Company, nif: nif)
+  def get_company_by_nif(nif) do
+    query = from(c in Company, where: c.nif == ^nif, preload: :users)
+    Repo.one(query)
+  end
 
   @doc """
   Creates a company.
diff --git a/lib/infin_web/controllers/user_registration_controller.ex b/lib/infin_web/controllers/user_registration_controller.ex
index c108b04..0640dfe 100644
--- a/lib/infin_web/controllers/user_registration_controller.ex
+++ b/lib/infin_web/controllers/user_registration_controller.ex
@@ -4,6 +4,7 @@ defmodule InfinWeb.UserRegistrationController do
   alias Infin.Accounts
   alias Infin.Accounts.User
   alias InfinWeb.UserAuth
+  alias Infin.Companies
 
   def new(conn, _params) do
     changeset = Accounts.change_user_registration(%User{})
@@ -11,6 +12,25 @@ defmodule InfinWeb.UserRegistrationController do
   end
 
   def create(conn, %{"user" => user_params}) do
+    company = Companies.get_company_by_nif(user_params["company"]["nif"])
+    if (not is_nil(company)) and company.users == []  do
+      user_params = Map.put(user_params, "company_id", company.id)
+      case Accounts.add_user(user_params) do
+        {:ok, user} ->
+          {:ok, _} =
+            Accounts.deliver_user_confirmation_instructions(
+              user,
+              &Routes.user_confirmation_url(conn, :confirm, &1)
+            )
+
+          conn
+          |> put_flash(:info, "User created successfully.")
+          |> UserAuth.log_in_user(user)
+
+        {:error, %Ecto.Changeset{} = changeset} ->
+          render(conn, "new.html", changeset: changeset)
+      end
+    end
     case Accounts.register_user(user_params) do
       {:ok, user} ->
         {:ok, _} =