diff --git a/account_usability/__manifest__.py b/account_usability/__manifest__.py
index 5fa7ff5..1399234 100644
--- a/account_usability/__manifest__.py
+++ b/account_usability/__manifest__.py
@@ -14,10 +14,13 @@ Account Usability
 
 The usability enhancements include:
 * show the supplier invoice number in the tree view of supplier invoices
-* add an *Overdue* filter on invoice search view (this feature was previously located in te module *account_invoice_overdue_filter*)
-* Increase the default limit of 80 lines in account move and account move line view.
-* Fast search on *Reconcile Ref* for account move line.
+* add an *Overdue* filter on invoice search view (this feature was previously 
+  located in te module *account_invoice_overdue_filter*)
+* increase the default limit of 80 lines in account move and account move line view.
+* fast search on *Reconcile Ref* for account move line.
 * disable reconciliation "guessing"
+* add sale dates to invoice report to be compliant with
+  https://www.service-public.fr/professionnels-entreprises/vosdroits/F31808
 
 Together with this module, I recommend the use of the following modules:
 * account_invoice_supplier_ref_unique (OCA project account-invoicing)
@@ -40,6 +43,7 @@ This module has been written by Alexis de Lattre from Akretion <alexis.delattre@
         'account_invoice_report_view.xml',
         'partner_view.xml',
         'wizard/account_invoice_mark_sent_view.xml',
+        'report/invoice_report.xml',
         ],
     'installable': True,
 }
diff --git a/account_usability/account.py b/account_usability/account.py
index 6fe2012..c195aac 100644
--- a/account_usability/account.py
+++ b/account_usability/account.py
@@ -37,6 +37,10 @@ class AccountInvoice(models.Model):
     has_attachment = fields.Boolean(
         compute='_compute_has_attachment',
         search='_search_has_attachment', readonly=True)
+    sale_dates = fields.Char(
+        compute="_compute_sales_dates", readonly=True,
+        help="This information appears on invoice qweb report "
+             "(you may use it for your own report)")
 
     def _compute_has_discount(self):
         prec = self.env['decimal.precision'].precision_get('Discount')
@@ -170,6 +174,24 @@ class AccountInvoice(models.Model):
         # ]
         return res
 
+    def _compute_sales_dates(self):
+        """ French law requires to set sale order dates into invoice
+            returned string: "sale1 (date1), sale2 (date2) ..."
+        """
+        for inv in self:
+            sales = inv.invoice_line_ids.mapped(
+                'sale_line_ids').mapped('order_id')
+            lang = inv.partner_id.commercial_partner_id.lang
+            date_format = self.env["res.lang"]._lang_get(
+                lang or "").date_format
+            dates = ["%s%s" % (
+                     x.name,
+                     x.confirmation_date and " (%s)" %
+                     # only when confirmation_date display it
+                     x.confirmation_date.strftime(date_format) or "")
+                     for x in sales]
+            inv.sale_dates = ", ".join(dates)
+
 
 class AccountInvoiceLine(models.Model):
     _inherit = 'account.invoice.line'
diff --git a/account_usability/report/invoice_report.xml b/account_usability/report/invoice_report.xml
new file mode 100644
index 0000000..e285a29
--- /dev/null
+++ b/account_usability/report/invoice_report.xml
@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<odoo>
+
+<template id="report_invoice_document" inherit_id="account.report_invoice_document">
+    <xpath expr="//div[@name='origin']/p" position="replace">
+        <p class="m-0" t-field="o.sale_dates"/>
+    </xpath>
+</template>
+
+</odoo>