diff --git a/cotisations/forms.py b/cotisations/forms.py
index 01e52756..73cb4971 100644
--- a/cotisations/forms.py
+++ b/cotisations/forms.py
@@ -46,7 +46,7 @@ from django.shortcuts import get_object_or_404
 
 from re2o.field_permissions import FieldPermissionFormMixin
 from re2o.mixins import FormRevMixin
-from .models import Article, Paiement, Facture, Banque, CustomInvoice
+from .models import Article, Paiement, Facture, Banque, CustomInvoice, Vente
 from .payment_methods import balance
 
 
@@ -104,7 +104,44 @@ class SelectArticleForm(FormRevMixin, Form):
         user = kwargs.pop('user')
         target_user = kwargs.pop('target_user', None)
         super(SelectArticleForm, self).__init__(*args, **kwargs)
-        self.fields['article'].queryset = Article.find_allowed_articles(user, target_user)
+        self.fields['article'].queryset = Article.find_allowed_articles(
+            user, target_user)
+
+
+class DiscountForm(Form):
+    """
+    Form used in oder to create a discount on an invoice.
+    """
+    is_relative = forms.BooleanField(
+        label=_("Discount is on percentage"),
+        required=False,
+    )
+    discount = forms.DecimalField(
+        label=_("Discount"),
+        max_value=100,
+        min_value=0,
+        max_digits=5,
+        decimal_places=2,
+        required=False,
+    )
+
+    def apply_to_invoice(self, invoice):
+        invoice_price = invoice.prix_total()
+        discount = self.cleaned_data['discount']
+        is_relative = self.cleaned_data['is_relative']
+        if is_relative:
+            amount = discount/100 * invoice_price
+        else:
+            amount = discount
+        if amount > 0:
+            name = _("{}% discount") if is_relative else _("{}€ discount")
+            name = name.format(discount)
+            Vente.objects.create(
+                facture=invoice,
+                name=name,
+                prix=-amount,
+                number=1
+            )
 
 
 class CustomInvoiceForm(FormRevMixin, ModelForm):
@@ -248,7 +285,8 @@ class RechargeForm(FormRevMixin, Form):
         super(RechargeForm, self).__init__(*args, **kwargs)
         self.fields['payment'].empty_label = \
             _("Select a payment method")
-        self.fields['payment'].queryset = Paiement.find_allowed_payments(user_source).exclude(is_balance=True)
+        self.fields['payment'].queryset = Paiement.find_allowed_payments(
+            user_source).exclude(is_balance=True)
 
     def clean(self):
         """
@@ -266,4 +304,3 @@ class RechargeForm(FormRevMixin, Form):
                 }
             )
         return self.cleaned_data
-
diff --git a/cotisations/templates/cotisations/facture.html b/cotisations/templates/cotisations/facture.html
index 1f87f579..ff9ed837 100644
--- a/cotisations/templates/cotisations/facture.html
+++ b/cotisations/templates/cotisations/facture.html
@@ -44,6 +44,8 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 {% blocktrans %}Current balance: {{ balance }} €{% endblocktrans %}
 </p>
 {% endif %}
+{% bootstrap_form_errors factureform %}
+{% bootstrap_form_errors discount_form %}
 
 <form class="form" method="post">
     {% csrf_token %}
@@ -68,8 +70,12 @@ with this program; if not, write to the Free Software Foundation, Inc.,
         {% endfor %}
     </div>
     <input class="btn btn-primary btn-block" role="button" value="{% trans "Add an extra article"%}" id="add_one">
+    <h3>{% trans "Discount" %}</h3>
+    {% if discount_form %}
+    {% bootstrap_form discount_form %}
+    {% endif %}
     <p>
-        {% blocktrans %}Total price: <span id="total_price">0,00</span> €{% endblocktrans %}
+    {% blocktrans %}Total price: <span id="total_price">0,00</span> €{% endblocktrans %}
     </p>
     {% endif %}
     {% bootstrap_button action_name button_type='submit' icon='ok' button_class='btn-success' %}
@@ -78,105 +84,117 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 {% if articlesformset or payment_method%}
 <script type="text/javascript">
 {% if articlesformset %}
-    var prices = {};
-    {% for article in articlelist %}
-    prices[{{ article.id|escapejs }}] = {{ article.prix }};
-    {% endfor %}
-
-    var template = `Article : &nbsp;
-        {% bootstrap_form articlesformset.empty_form label_class='sr-only' %}
-        &nbsp;
-        <button class="btn btn-danger btn-sm"
-        id="id_form-__prefix__-article-remove" type="button">
-        <span class="fa fa-times"></span>
-        </button>`
-
-    function add_article(){
-        // Index start at 0 => new_index = number of items
-        var new_index =
-            document.getElementsByClassName('product_to_sell').length;
-        document.getElementById('id_form-TOTAL_FORMS').value ++;
-        var new_article = document.createElement('div');
-        new_article.className = 'product_to_sell form-inline';
-        new_article.innerHTML = template.replace(/__prefix__/g, new_index);
-        document.getElementById('form_set').appendChild(new_article);
-        add_listenner_for_id(new_index);
-    }
-
-    function update_price(){
-        var price = 0;
-        var product_count =
-            document.getElementsByClassName('product_to_sell').length;
-        var article, article_price, quantity;
-        for (i = 0; i < product_count; ++i){
-            article = document.getElementById(
+var prices = {};
+{% for article in articlelist %}
+prices[{{ article.id|escapejs }}] = {{ article.prix }};
+{% endfor %}
+
+var template = `Article : &nbsp;
+{% bootstrap_form articlesformset.empty_form label_class='sr-only' %}
+&nbsp;
+<button class="btn btn-danger btn-sm"
+id="id_form-__prefix__-article-remove" type="button">
+<span class="fa fa-times"></span>
+</button>`
+
+function add_article(){
+    // Index start at 0 => new_index = number of items
+    var new_index =
+        document.getElementsByClassName('product_to_sell').length;
+    document.getElementById('id_form-TOTAL_FORMS').value ++;
+    var new_article = document.createElement('div');
+    new_article.className = 'product_to_sell form-inline';
+    new_article.innerHTML = template.replace(/__prefix__/g, new_index);
+    document.getElementById('form_set').appendChild(new_article);
+    add_listenner_for_id(new_index);
+}
+
+function update_price(){
+    var price = 0;
+    var product_count =
+        document.getElementsByClassName('product_to_sell').length;
+    var article, article_price, quantity;
+    for (i = 0; i < product_count; ++i){
+        article = document.getElementById(
                 'id_form-' + i.toString() + '-article').value;
-            if (article == '') {
-                continue;
-            }
-            article_price = prices[article];
-            quantity = document.getElementById(
-                'id_form-' + i.toString() + '-quantity').value;
-            price += article_price * quantity;
+        if (article == '') {
+            continue;
         }
-        document.getElementById('total_price').innerHTML =
-            price.toFixed(2).toString().replace('.', ',');
+        article_price = prices[article];
+        quantity = document.getElementById(
+                'id_form-' + i.toString() + '-quantity').value;
+        price += article_price * quantity;
     }
-
-    function add_listenner_for_id(i){
-        document.getElementById('id_form-' + i.toString() + '-article')
-            .addEventListener("change", update_price, true);
-        document.getElementById('id_form-' + i.toString() + '-article')
-            .addEventListener("onkeypress", update_price, true);
-        document.getElementById('id_form-' + i.toString() + '-quantity')
-            .addEventListener("change", update_price, true);
-        document.getElementById('id_form-' + i.toString() + '-article-remove')
-            .addEventListener("click", function(event) {
-                var article = event.target.parentNode;
-                article.parentNode.removeChild(article);
-                document.getElementById('id_form-TOTAL_FORMS').value --;
-                update_price();
-            })
+    {% if discount_form %}
+    var relative_discount = document.getElementById('id_is_relative').checked;
+    var discount = document.getElementById('id_discount').value;
+    if(relative_discount) {
+        discount = discount/100 * price;
     }
-
-    // Add events manager when DOM is fully loaded
-    document.addEventListener("DOMContentLoaded", function() {
-        document.getElementById("add_one")
-            .addEventListener("click", add_article, true);
-        var product_count =
-            document.getElementsByClassName('product_to_sell').length;
-        for (i = 0; i < product_count; ++i){
-            add_listenner_for_id(i);
-        }
-        update_price();
-    });
+    price -= discount;
+    {% endif %}
+    document.getElementById('total_price').innerHTML =
+        price.toFixed(2).toString().replace('.', ',');
+}
+
+function add_listenner_for_id(i){
+    document.getElementById('id_form-' + i.toString() + '-article')
+        .addEventListener("change", update_price, true);
+    document.getElementById('id_form-' + i.toString() + '-article')
+        .addEventListener("onkeypress", update_price, true);
+    document.getElementById('id_form-' + i.toString() + '-quantity')
+        .addEventListener("change", update_price, true);
+    document.getElementById('id_form-' + i.toString() + '-article-remove')
+        .addEventListener("click", function(event) {
+            var article = event.target.parentNode;
+            article.parentNode.removeChild(article);
+            document.getElementById('id_form-TOTAL_FORMS').value --;
+            update_price();
+        })
+}
+
+// Add events manager when DOM is fully loaded
+document.addEventListener("DOMContentLoaded", function() {
+    document.getElementById("add_one")
+        .addEventListener("click", add_article, true);
+    var product_count =
+        document.getElementsByClassName('product_to_sell').length;
+    for (i = 0; i < product_count; ++i){
+        add_listenner_for_id(i);
+    }
+    document.getElementById('id_discount')
+        .addEventListener('change', update_price, true);
+    document.getElementById('id_is_relative')
+        .addEventListener('click', update_price, true);
+    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;
+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;
     }
-    document.getElementById("paymentMethodSelect").addEventListener("change", update_payment_method_form);
+    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/tex.py b/cotisations/tex.py
index 3f404f22..d6c0ae5f 100644
--- a/cotisations/tex.py
+++ b/cotisations/tex.py
@@ -36,6 +36,7 @@ from django.template import Context
 from django.http import HttpResponse
 from django.conf import settings
 from django.utils.text import slugify
+import logging
 
 
 TEMP_PREFIX = getattr(settings, 'TEX_TEMP_PREFIX', 'render_tex-')
@@ -93,6 +94,20 @@ def create_pdf(template, ctx={}):
     return pdf
 
 
+def escape_chars(string):
+    """Escape the '%' and the '€' signs to avoid messing with LaTeX"""
+    if not isinstance(string, str):
+        return string
+    mapping = (
+        ('€', r'\euro'),
+        ('%', r'\%'),
+    )
+    r = str(string)
+    for k, v in mapping:
+        r = r.replace(k, v)
+    return r
+
+
 def render_tex(_request, template, ctx={}):
     """Creates a PDF from a LaTex templates using pdflatex.
 
diff --git a/cotisations/views.py b/cotisations/views.py
index 68118711..7d4185cc 100644
--- a/cotisations/views.py
+++ b/cotisations/views.py
@@ -80,9 +80,10 @@ from .forms import (
     DelBanqueForm,
     SelectArticleForm,
     RechargeForm,
-    CustomInvoiceForm
+    CustomInvoiceForm,
+    DiscountForm
 )
-from .tex import render_invoice
+from .tex import render_invoice, escape_chars
 from .payment_methods.forms import payment_method_factory
 from .utils import find_payment_method
 
@@ -198,8 +199,9 @@ def new_custom_invoice(request):
         request.POST or None,
         form_kwargs={'user': request.user}
     )
+    discount_form = DiscountForm(request.POST or None)
 
-    if invoice_form.is_valid() and articles_formset.is_valid():
+    if invoice_form.is_valid() and articles_formset.is_valid() and discount_form.is_valid():
         new_invoice_instance = invoice_form.save()
         for art_item in articles_formset:
             if art_item.cleaned_data:
@@ -213,6 +215,7 @@ def new_custom_invoice(request):
                     duration=article.duration,
                     number=quantity
                 )
+        discount_form.apply_to_invoice(new_invoice_instance)
         messages.success(
             request,
             _("The custom invoice was created.")
@@ -223,7 +226,8 @@ def new_custom_invoice(request):
         'factureform': invoice_form,
         'action_name': _("Confirm"),
         'articlesformset': articles_formset,
-        'articlelist': articles
+        'articlelist': articles,
+        'discount_form': discount_form
     }, 'cotisations/facture.html', request)
 
 
@@ -382,7 +386,7 @@ def custom_invoice_pdf(request, invoice, **_kwargs):
     purchases_info = []
     for purchase in purchases_objects:
         purchases_info.append({
-            'name': purchase.name,
+            'name': escape_chars(purchase.name),
             'price': purchase.prix,
             'quantity': purchase.number,
             'total_price': purchase.prix_total