diff --git a/cotisations/forms.py b/cotisations/forms.py
index a5db7b92..0ee4c143 100644
--- a/cotisations/forms.py
+++ b/cotisations/forms.py
@@ -242,17 +242,12 @@ class PaiementForm(FormRevMixin, ModelForm):
     class Meta:
         model = Paiement
         # TODO : change moyen to method and type_paiement to payment_type
-        fields = ['moyen', 'type_paiement', 'allow_self_subscription']
+        fields = ['moyen', 'allow_self_subscription']
 
     def __init__(self, *args, **kwargs):
         prefix = kwargs.pop('prefix', self.Meta.model.__name__)
         super(PaiementForm, self).__init__(*args, prefix=prefix, **kwargs)
         self.fields['moyen'].label = _("Payment method name")
-        self.fields['type_paiement'].label = _("Payment type")
-        self.fields['type_paiement'].help_text = \
-            _("The payement type is used for specific behaviour.\
-            The \"cheque\" type means a cheque number and a bank name\
-            may be added when using this payment method.")
 
 
 # TODO : change paiement to payment
diff --git a/cotisations/migrations/0032_chequepayment_comnpaypayment.py b/cotisations/migrations/0032_chequepayment_comnpaypayment.py
index 76fc4ea0..d2c67308 100644
--- a/cotisations/migrations/0032_chequepayment_comnpaypayment.py
+++ b/cotisations/migrations/0032_chequepayment_comnpaypayment.py
@@ -1,8 +1,9 @@
 # -*- coding: utf-8 -*-
-# Generated by Django 1.10.7 on 2018-06-28 17:28
+# Generated by Django 1.10.7 on 2018-07-02 18:56
 from __future__ import unicode_literals
 
 import cotisations.payment_methods.comnpay.aes_field
+import cotisations.payment_methods.models
 from django.db import migrations, models
 import django.db.models.deletion
 
@@ -29,6 +30,8 @@ def add_comnpay(apps, schema_editor):
     comnpay.payment_pass = options.payment_pass
     comnpay.payment = payment
     comnpay.save()
+    payment.moyen = "ComnPay"
+    payment.save()
 
 
 class Migration(migrations.Migration):
@@ -42,18 +45,20 @@ class Migration(migrations.Migration):
             name='ChequePayment',
             fields=[
                 ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
-                ('payment', models.OneToOneField(on_delete=django.db.models.deletion.CASCADE, related_name='payment_method', to='cotisations.Paiement')),
+                ('payment', models.OneToOneField(editable=False, on_delete=django.db.models.deletion.CASCADE, related_name='payment_method', to='cotisations.Paiement')),
             ],
+            bases=(cotisations.payment_methods.models.PaymentMethodMixin, models.Model),
         ),
         migrations.CreateModel(
             name='ComnpayPayment',
             fields=[
                 ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
-                ('payment_user', models.CharField(blank=True, default='', max_length=255)),
+                ('payment_credential', models.CharField(blank=True, default='', max_length=255)),
                 ('payment_pass', cotisations.payment_methods.comnpay.aes_field.AESEncryptedField(blank=True, max_length=255, null=True)),
-                ('payment', models.OneToOneField(on_delete=django.db.models.deletion.CASCADE, related_name='payment_method', to='cotisations.Paiement')),
+                ('payment', models.OneToOneField(editable=False, on_delete=django.db.models.deletion.CASCADE, related_name='payment_method', to='cotisations.Paiement')),
             ],
+            bases=(cotisations.payment_methods.models.PaymentMethodMixin, models.Model),
         ),
-        migrations.RunPython(add_cheque),
         migrations.RunPython(add_comnpay),
+        migrations.RunPython(add_cheque),
     ]
diff --git a/cotisations/migrations/0033_auto_20180628_2157.py b/cotisations/migrations/0033_auto_20180628_2157.py
deleted file mode 100644
index 51509105..00000000
--- a/cotisations/migrations/0033_auto_20180628_2157.py
+++ /dev/null
@@ -1,20 +0,0 @@
-# -*- coding: utf-8 -*-
-# Generated by Django 1.10.7 on 2018-06-28 19:57
-from __future__ import unicode_literals
-
-from django.db import migrations, models
-
-
-class Migration(migrations.Migration):
-
-    dependencies = [
-        ('cotisations', '0032_chequepayment_comnpaypayment'),
-    ]
-
-    operations = [
-        migrations.AlterField(
-            model_name='comnpaypayment',
-            name='payment_id',
-            field=models.CharField(blank=True, default='', max_length=255),
-        ),
-    ]
diff --git a/cotisations/payment_methods/__init__.py b/cotisations/payment_methods/__init__.py
index cc21f42b..36904411 100644
--- a/cotisations/payment_methods/__init__.py
+++ b/cotisations/payment_methods/__init__.py
@@ -1,4 +1,5 @@
 from django.conf.urls import include, url
+from django.utils.translation import ugettext_lazy as _l
 
 from . import comnpay, cheque
 
@@ -7,3 +8,18 @@ urlpatterns = [
     url(r'^comnpay/', include(comnpay.urls, namespace='comnpay')),
     url(r'^cheque/', include(cheque.urls, namespace='cheque')),
 ]
+
+PAYMENT_METHODS = [
+    comnpay,
+    cheque,
+]
+
+
+def find_payment_method(payment):
+    for method in PAYMENT_METHODS:
+        try:
+            o = method.PaymentMethod.objects.get(payment=payment)
+            return o
+        except method.PaymentMethod.DoesNotExist:
+            pass
+    return None
diff --git a/cotisations/payment_methods/cheque/__init__.py b/cotisations/payment_methods/cheque/__init__.py
index 6610cdd8..a6fef640 100644
--- a/cotisations/payment_methods/cheque/__init__.py
+++ b/cotisations/payment_methods/cheque/__init__.py
@@ -4,4 +4,4 @@ This module contains a method to pay online using cheque.
 from . import models, urls, views
 NAME = "CHEQUE"
 
-Payment = models.ChequePayment
+PaymentMethod = models.ChequePayment
diff --git a/cotisations/payment_methods/cheque/forms.py b/cotisations/payment_methods/cheque/forms.py
index 892ba190..ae816a4b 100644
--- a/cotisations/payment_methods/cheque/forms.py
+++ b/cotisations/payment_methods/cheque/forms.py
@@ -1,10 +1,12 @@
 from django import forms
 from django.utils.translation import ugettext_lazy as _l
 
-from cotisations.models import Banque as Bank
+from re2o.mixins import FormRevMixin
+from cotisations.models import Facture as Invoice
 
 
-class ChequeForm(forms.Form):
+class InvoiceForm(FormRevMixin, forms.ModelForm):
     """A simple form to get the bank a the cheque number."""
-    bank = forms.ModelChoiceField(Bank.objects.all(), label=_l("Bank"))
-    number = forms.CharField(label=_l("Cheque number"))
+    class Meta:
+        model = Invoice
+        fields = ['banque', 'cheque']
diff --git a/cotisations/payment_methods/cheque/models.py b/cotisations/payment_methods/cheque/models.py
index 336f025e..29c86a41 100644
--- a/cotisations/payment_methods/cheque/models.py
+++ b/cotisations/payment_methods/cheque/models.py
@@ -2,16 +2,19 @@ from django.db import models
 from django.shortcuts import redirect
 from django.urls import reverse
 
-from cotisations.models import Paiement as BasePayment
+from cotisations.models import Paiement
+from cotisations.payment_methods.mixins import PaymentMethodMixin
 
 
-class ChequePayment(models.Model):
+class ChequePayment(PaymentMethodMixin, models.Model):
     """
-    The model allowing you to pay with a cheque. It redefines post_payment
-    method. See `cotisations.models.Paiement for further details.
+    The model allowing you to pay with a cheque.
     """
-    payment = models.OneToOneField(BasePayment, related_name='payment_method')
-
+    payment = models.OneToOneField(
+        Paiement,
+        related_name='payment_method',
+        editable=False
+    )
     def end_payment(self, invoice, request):
         invoice.valid = False
         invoice.save()
diff --git a/cotisations/payment_methods/comnpay/__init__.py b/cotisations/payment_methods/comnpay/__init__.py
index d0289364..58433c80 100644
--- a/cotisations/payment_methods/comnpay/__init__.py
+++ b/cotisations/payment_methods/comnpay/__init__.py
@@ -3,4 +3,4 @@ This module contains a method to pay online using comnpay.
 """
 from . import models, urls, views
 NAME = "COMNPAY"
-Payment = models.ComnpayPayment
+PaymentMethod = models.ComnpayPayment
diff --git a/cotisations/payment_methods/comnpay/models.py b/cotisations/payment_methods/comnpay/models.py
index 4fc509af..68f883d4 100644
--- a/cotisations/payment_methods/comnpay/models.py
+++ b/cotisations/payment_methods/comnpay/models.py
@@ -1,19 +1,22 @@
 from django.db import models
 from django.shortcuts import render
 
-from cotisations.models import Paiement as BasePayment
+from cotisations.models import Paiement
+from cotisations.payment_methods.mixins import PaymentMethodMixin
 
 from .aes_field import AESEncryptedField
 from .views import comnpay
 
 
-class ComnpayPayment(models.Model):
+class ComnpayPayment(PaymentMethodMixin, models.Model):
     """
-    The model allowing you to pay with COMNPAY. It redefines post_payment
-    method. See `cotisations.models.Paiement for further details.
+    The model allowing you to pay with COMNPAY.
     """
-    payment = models.OneToOneField(BasePayment, related_name='payment_method')
-
+    payment = models.OneToOneField(
+        Paiement,
+        related_name='payment_method',
+        editable=False
+    )
     payment_credential = models.CharField(
         max_length=255,
         default='',
diff --git a/cotisations/payment_methods/forms.py b/cotisations/payment_methods/forms.py
new file mode 100644
index 00000000..2acc80f0
--- /dev/null
+++ b/cotisations/payment_methods/forms.py
@@ -0,0 +1,59 @@
+from django import forms
+from django.utils.translation import ugettext as _
+from django.utils.translation import ugettext_lazy as _l
+
+from . import PAYMENT_METHODS, find_payment_method
+
+
+def payment_method_factory(payment, *args, **kwargs):
+    payment_method = kwargs.pop('instance', find_payment_method(payment))
+    if payment_method is not None:
+        return forms.modelform_factory(type(payment_method), fields='__all__')(
+            *args,
+            instance=payment_method,
+            **kwargs
+        )
+    return PaymentMethodForm(payment_method, *args, **kwargs)
+
+
+class PaymentMethodForm(forms.Form):
+    """A special form which allows you to add a payment method to a `Payment`
+    objects if it hasn't one yet, or to edit the existing payment method.
+
+    To do so it replaces itself with a `modelform_factory`.
+    """
+
+    payment_method = forms.ChoiceField(
+        label=_l("Special payment method"),
+        required=False
+    )
+
+    def __init__(self, payment_method, *args, **kwargs):
+        super(PaymentMethodForm, self).__init__(*args, **kwargs)
+        if payment_method is None:
+            prefix = kwargs.get('prefix', None)
+            self.fields['payment_method'].choices = [(i,p.NAME) for (i,p) in enumerate(PAYMENT_METHODS)]
+            self.fields['payment_method'].choices.insert(0, ('', _l('no')))
+            self.fields['payment_method'].widget.attrs = {
+                'id': 'paymentMethodSelect'
+            }
+            self.templates = [
+                forms.modelform_factory(p.PaymentMethod, fields='__all__')(prefix=prefix)
+                for p in PAYMENT_METHODS
+            ]
+        else:
+            self.fields = {}
+
+    def save(self, *args, payment=None, **kwargs):
+        commit = kwargs.pop('commit', True)
+        choice = self.cleaned_data['payment_method']
+        if choice=='':
+            return
+        choice = int(choice)
+        model = PAYMENT_METHODS[choice].PaymentMethod
+        form = forms.modelform_factory(model, fields='__all__')(self.data, prefix=self.prefix)
+        payment_method = form.save(commit=False)
+        payment_method.payment = payment
+        if commit:
+            payment_method.save()
+        return payment_method
diff --git a/cotisations/payment_methods/mixins.py b/cotisations/payment_methods/mixins.py
new file mode 100644
index 00000000..62ebbf32
--- /dev/null
+++ b/cotisations/payment_methods/mixins.py
@@ -0,0 +1,21 @@
+from django.db import models
+
+from cotisations.models import Paiement
+
+
+class PaymentMethodMixin:
+    """The base class for payment models. They should inherit from this."""
+    payment = models.OneToOneField(
+        Paiement,
+        related_name='payment_method',
+        editable=False
+    )
+
+    def end_payment(self, invoice, request):
+        """Redefine this method in order to get a different ending to the
+        payment session if you whish.
+
+        Must return a HttpResponse-like object.
+        """
+        return self.payment.end_payment(
+            invoice, request, use_payment_method=False)
diff --git a/cotisations/templates/cotisations/facture.html b/cotisations/templates/cotisations/facture.html
index dc8648ac..082759c4 100644
--- a/cotisations/templates/cotisations/facture.html
+++ b/cotisations/templates/cotisations/facture.html
@@ -57,16 +57,21 @@ with this program; if not, write to the Free Software Foundation, Inc.,
     </p>
     {% endif %}
     {% bootstrap_form factureform %}
+    {% if payment_method %}
+    {% bootstrap_form payment_method %}
+    <div id="paymentMethod"></div>
+    {% endif %}
     {% bootstrap_button action_name button_type='submit' icon='star' %}
 </form>
 
-{% if articlesformset %}
+{% if articlesformset or payment_method%}
 <script type="text/javascript">
+{% if articlesformset %}
     var prices = {};
     {% for article in articles %}
     prices[{{ article.id|escapejs }}] = {{ article.prix }};
     {% endfor %}
- 
+
     var template = `Article : &nbsp;
         {% bootstrap_form articlesformset.empty_form label_class='sr-only' %}
         &nbsp;
@@ -134,6 +139,34 @@ with this program; if not, write to the Free Software Foundation, Inc.,
         }
         update_price();
     });
+{% endif %}
+{% if payment_method.templates %}
+    var TEMPLATES = [
+        "",
+        {% for t in payment_method.templates %}
+        {% if t %}
+        `{% bootstrap_form t %}`,
+        {% else %}
+        "",
+        {% endif %}
+        {% endfor %}
+    ];
+    function update_payment_method_form(){
+        var method = document.getElementById('paymentMethodSelect').value;
+        if(method==""){
+            method=0;
+        }
+        else{
+            method = Number(method);
+            method += 1;
+        }
+        console.log(method);
+        var html = TEMPLATES[method];
+
+        document.getElementById('paymentMethod').innerHTML = html;
+    }
+    document.getElementById("paymentMethodSelect").addEventListener("change", update_payment_method_form);
+{% endif %}
 </script>
 {% endif %}
 
diff --git a/cotisations/views.py b/cotisations/views.py
index ea137379..280a3aa9 100644
--- a/cotisations/views.py
+++ b/cotisations/views.py
@@ -74,6 +74,7 @@ from .forms import (
     RechargeForm
 )
 from .tex import render_invoice
+from .payment_methods.forms import payment_method_factory
 
 
 @login_required
@@ -473,9 +474,15 @@ def add_paiement(request):
     """
     View used to add a payment method.
     """
-    payment = PaiementForm(request.POST or None)
-    if payment.is_valid():
-        payment.save()
+    payment = PaiementForm(request.POST or None, prefix='payment')
+    payment_method = payment_method_factory(
+        payment.instance,
+        request.POST or None,
+        prefix='payment_method'
+    )
+    if payment.is_valid() and payment_method.is_valid():
+        payment = payment.save()
+        payment_method.save(payment=payment)
         messages.success(
             request,
             _("The payment method has been successfully created.")
@@ -483,6 +490,7 @@ def add_paiement(request):
         return redirect(reverse('cotisations:index-paiement'))
     return form({
         'factureform': payment,
+        'payment_method': payment_method,
         'action_name': _("Add")
         }, 'cotisations/facture.html', request)
 
@@ -494,17 +502,28 @@ def edit_paiement(request, paiement_instance, **_kwargs):
     """
     View used to edit a payment method.
     """
-    payment = PaiementForm(request.POST or None, instance=paiement_instance)
-    if payment.is_valid():
-        if payment.changed_data:
-            payment.save()
-            messages.success(
-                request,
-                _("The payement method has been successfully edited.")
-            )
+    payment = PaiementForm(
+        request.POST or None,
+        instance=paiement_instance,
+        prefix="payment"
+    )
+    payment_method = payment_method_factory(
+        paiement_instance,
+        request.POST or None,
+        prefix='payment_method'
+    )
+
+    if payment.is_valid() and payment_method.is_valid():
+        payment.save()
+        payment_method.save()
+        messages.success(
+            request,
+            _("The payement method has been successfully edited.")
+        )
         return redirect(reverse('cotisations:index-paiement'))
     return form({
         'factureform': payment,
+        'payment_method': payment_method,
         'action_name': _("Edit")
         }, 'cotisations/facture.html', request)