diff --git a/note/admin.py b/note/admin.py
index e634e607..66623f58 100644
--- a/note/admin.py
+++ b/note/admin.py
@@ -4,7 +4,7 @@
 
 from django.contrib import admin
 
-from .models.notes import Alias, NoteClub, NoteSpecial, NoteUser
+from .models.notes import Alias, Note, NoteClub, NoteSpecial, NoteUser
 from .models.transactions import MembershipTransaction, Transaction, \
     TransactionTemplate
 
@@ -26,8 +26,8 @@ class NoteClubAdmin(admin.ModelAdmin):
     list_filter = ('is_active',)
     search_fields = ['club__name']
 
-    # We can't change club after creation
-    readonly_fields = ('club',)
+    # We can't change club after creation or the balance
+    readonly_fields = ('club', 'balance')
 
     def has_add_permission(self, request):
         """
@@ -62,8 +62,8 @@ class NoteUserAdmin(admin.ModelAdmin):
     date_hierarchy = 'user__date_joined'
     ordering = ['-user__date_joined']
 
-    # We can't change user after creation
-    readonly_fields = ('user',)
+    # We can't change user after creation or the balance
+    readonly_fields = ('user', 'balance')
 
     def has_add_permission(self, request):
         """
diff --git a/note/models/notes.py b/note/models/notes.py
index 499678d9..67965a7b 100644
--- a/note/models/notes.py
+++ b/note/models/notes.py
@@ -7,17 +7,16 @@ from django.db import models
 from django.db.models.signals import post_save
 from django.dispatch import receiver
 from django.utils.translation import gettext_lazy as _
+from polymorphic.models import PolymorphicModel
 
 """
 Defines each note types
 """
 
 
-class Note(models.Model):
+class Note(PolymorphicModel):
     """
     An model, use to add transactions capabilities
-
-    We do not use an abstract model to simplify the transfer between two notes.
     """
     balance = models.IntegerField(
         verbose_name=_('account balance'),
@@ -57,6 +56,9 @@ class NoteUser(Note):
         verbose_name = _("one's note")
         verbose_name_plural = _("users note")
 
+    def __str__(self):
+        return _("%(user)s's note") % {'user': str(self.user)}
+
 
 class NoteClub(Note):
     """
diff --git a/note/models/transactions.py b/note/models/transactions.py
index 753f4925..ce74fab7 100644
--- a/note/models/transactions.py
+++ b/note/models/transactions.py
@@ -26,6 +26,7 @@ class TransactionTemplate(models.Model):
     )
     amount = models.PositiveIntegerField(
         verbose_name=_('amount'),
+        help_text=_('in centimes'),
     )
     template_type = models.CharField(
         verbose_name=_('type'),
diff --git a/note_kfet/settings.py b/note_kfet/settings.py
index a4f837e9..65a69983 100644
--- a/note_kfet/settings.py
+++ b/note_kfet/settings.py
@@ -32,6 +32,11 @@ INSTALLED_APPS = [
     # Theme overrides Django Admin templates
     'theme',
 
+    # External apps
+    'polymorphic',
+    'guardian',
+    'reversion',
+
     # Django contrib
     'django.contrib.admin',
     'django.contrib.admindocs',
@@ -42,10 +47,6 @@ INSTALLED_APPS = [
     'django.contrib.messages',
     'django.contrib.staticfiles',
 
-    # External apps
-    'guardian',
-    'reversion',
-
     # Note apps
     'activity',
     'member',
@@ -120,6 +121,8 @@ AUTHENTICATION_BACKENDS = (
     'guardian.backends.ObjectPermissionBackend',
 )
 
+GUARDIAN_GET_CONTENT_TYPE = 'polymorphic.contrib.guardian.get_polymorphic_base_content_type'
+
 # Internationalization
 # https://docs.djangoproject.com/en/2.2/topics/i18n/
 
diff --git a/requirements.txt b/requirements.txt
index 6201c93e..79e89f20 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -5,4 +5,5 @@ Pillow==6.1.0
 pytz==2019.1
 six==1.12.0
 sqlparse==0.3.0
-django-reversion==3.0.3
\ No newline at end of file
+django-reversion==3.0.3
+django-polymorphic==2.0.3
\ No newline at end of file