diff --git a/app/models/user.rb b/app/models/user.rb
index f5a05e3ba..f652a8f9c 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -25,6 +25,7 @@ class User < ActiveRecord::Base
 
   validates :username, presence: true, unless: :organization?
   validates :username, uniqueness: true, unless: :organization?
+  validates :document_number, uniqueness: { scope: :document_type }, allow_nil: true
   validate :validate_username_length
 
   validates :official_level, inclusion: {in: 0..5}
@@ -44,6 +45,8 @@ class User < ActiveRecord::Base
   scope :for_render,     -> { includes(:organization) }
   scope :by_document,    -> (document_type, document_number) { where(document_type: document_type, document_number: document_number) }
 
+  before_validation :clean_document_number
+
   def self.find_for_oauth(auth, signed_in_resource = nil)
     # Get the identity and user if they exist
     identity = Identity.find_for_oauth(auth)
@@ -171,6 +174,10 @@ class User < ActiveRecord::Base
 
   private
 
+    def clean_document_number
+      self.document_number = self.document_number.gsub(/[^a-z0-9]+/i, "").upcase unless self.document_number.blank?
+    end
+
     def validate_username_length
       validator = ActiveModel::Validations::LengthValidator.new(
         attributes: :username,
diff --git a/spec/models/user_spec.rb b/spec/models/user_spec.rb
index 29b239da9..14f20ad1d 100644
--- a/spec/models/user_spec.rb
+++ b/spec/models/user_spec.rb
@@ -287,4 +287,19 @@ describe User do
 
   end
 
+  describe "document_number" do
+    it "should upcase document number" do
+      user = User.new({document_number: "x1234567z"})
+      user.valid?
+      expect(user.document_number).to eq("X1234567Z")
+    end
+
+    it "should remove all characters except numbers and letters" do
+      user = User.new({document_number: " 12.345.678 - B"})
+      user.valid?
+      expect(user.document_number).to eq("12345678B")
+    end
+
+  end
+
 end