diff --git a/taiga/users/api.py b/taiga/users/api.py
index d72d021d..20031395 100644
--- a/taiga/users/api.py
+++ b/taiga/users/api.py
@@ -35,7 +35,7 @@ from taiga.base.api.utils import get_object_or_404
 from taiga.base.filters import MembersFilterBackend
 from taiga.base.mails import mail_builder
 from taiga.projects.votes import services as votes_service
-
+from taiga.users.services import get_user_by_username_or_email
 from easy_thumbnails.source_generators import pil_image
 
 from . import models
@@ -145,13 +145,7 @@ class UsersViewSet(ModelCrudViewSet):
         if not username_or_email:
             raise exc.WrongArguments(_("Invalid username or email"))
 
-        try:
-            queryset = models.User.objects.all()
-            user = queryset.get(Q(username=username_or_email) |
-                                    Q(email=username_or_email))
-        except models.User.DoesNotExist:
-            raise exc.WrongArguments(_("Invalid username or email"))
-
+        user = get_user_by_username_or_email(username_or_email)
         user.token = str(uuid.uuid1())
         user.save(update_fields=["token"])
 
diff --git a/taiga/users/services.py b/taiga/users/services.py
index 3ef4672d..5dd8bc0f 100644
--- a/taiga/users/services.py
+++ b/taiga/users/services.py
@@ -37,6 +37,24 @@ from .gravatar import get_gravatar_url
 
 from django.conf import settings
 
+
+def get_user_by_username_or_email(username_or_email):
+    user_model = apps.get_model("users", "User")
+    qs = user_model.objects.filter(Q(username__iexact=username_or_email) |
+                                   Q(email__iexact=username_or_email))
+
+    if len(qs) > 1:
+        qs = qs.filter(Q(username=username_or_email) |
+                       Q(email=username_or_email))
+
+    if len(qs) == 0:
+        raise exc.WrongArguments(_("Username or password does not matches user."))
+
+    user = qs[0]
+    return user
+
+
+
 def get_and_validate_user(*, username:str, password:str) -> bool:
     """
     Check if user with username/email exists and specified
@@ -46,13 +64,7 @@ def get_and_validate_user(*, username:str, password:str) -> bool:
     exception is raised.
     """
 
-    user_model = apps.get_model("users", "User")
-    qs = user_model.objects.filter(Q(username=username) |
-                                   Q(email=username))
-    if len(qs) == 0:
-        raise exc.WrongArguments(_("Username or password does not matches user."))
-
-    user = qs[0]
+    user = get_user_by_username_or_email(username)
     if not user.check_password(password):
         raise exc.WrongArguments(_("Username or password does not matches user."))
 
diff --git a/tests/integration/test_auth_api.py b/tests/integration/test_auth_api.py
index e7a7805a..02df17fa 100644
--- a/tests/integration/test_auth_api.py
+++ b/tests/integration/test_auth_api.py
@@ -106,3 +106,67 @@ def test_respond_400_if_username_or_email_is_duplicate(client, settings, registe
     register_form["email"] = "ff@dd.com"
     response = client.post(reverse("auth-register"), register_form)
     assert response.status_code == 400
+
+
+def test_auth_uppercase_ignore(client, settings):
+    settings.PUBLIC_REGISTER_ENABLED = True
+
+    register_form = {"username": "Username",
+                     "password": "password",
+                     "full_name": "fname",
+                     "email": "User@email.com",
+                     "type": "public"}
+    response = client.post(reverse("auth-register"), register_form)
+
+    #Only exists one user with the same lowercase version of username/password
+    login_form = {"type": "normal",
+                  "username": "Username",
+                  "password": "password"}
+
+    response = client.post(reverse("auth-list"), login_form)
+    assert response.status_code == 200
+
+    login_form = {"type": "normal",
+                  "username": "User@email.com",
+                  "password": "password"}
+
+    response = client.post(reverse("auth-list"), login_form)
+    assert response.status_code == 200
+
+    #Now we have two users with the same lowercase version of username/password
+    # 1.- The capitalized version works
+    register_form = {"username": "username",
+                     "password": "password",
+                     "full_name": "fname",
+                     "email": "user@email.com",
+                     "type": "public"}
+    response = client.post(reverse("auth-register"), register_form)
+
+    login_form = {"type": "normal",
+                  "username": "Username",
+                  "password": "password"}
+
+    response = client.post(reverse("auth-list"), login_form)
+    assert response.status_code == 200
+
+    login_form = {"type": "normal",
+                  "username": "User@email.com",
+                  "password": "password"}
+
+    response = client.post(reverse("auth-list"), login_form)
+    assert response.status_code == 200
+
+    # 2.- If we capitalize a new version it doesn't
+    login_form = {"type": "normal",
+                  "username": "uSername",
+                  "password": "password"}
+
+    response = client.post(reverse("auth-list"), login_form)
+    assert response.status_code == 400
+
+    login_form = {"type": "normal",
+                  "username": "uSer@email.com",
+                  "password": "password"}
+
+    response = client.post(reverse("auth-list"), login_form)
+    assert response.status_code == 400