diff --git a/addons/l10n_fi/__manifest__.py b/addons/l10n_fi/__manifest__.py
index d4841bff4dc..d7a11bf39a2 100644
--- a/addons/l10n_fi/__manifest__.py
+++ b/addons/l10n_fi/__manifest__.py
@@ -17,6 +17,7 @@ After installing this module, you'll have access to :
     * Finnish chart of account
     * Fiscal positions
     * Invoice Payment Reference Types (Finnish Standard Reference & Finnish Creditor Reference (RF))
+    * Finnish Reference format for Sale Orders
 
 Set the payment reference type from the Sales Journal.
     """,
diff --git a/addons/l10n_fi_sale/__init__.py b/addons/l10n_fi_sale/__init__.py
new file mode 100644
index 00000000000..b60115f0aa5
--- /dev/null
+++ b/addons/l10n_fi_sale/__init__.py
@@ -0,0 +1,4 @@
+#-*- coding:utf-8 -*-
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+
+from . import models
diff --git a/addons/l10n_fi_sale/__manifest__.py b/addons/l10n_fi_sale/__manifest__.py
new file mode 100644
index 00000000000..0bde5be3498
--- /dev/null
+++ b/addons/l10n_fi_sale/__manifest__.py
@@ -0,0 +1,17 @@
+# -*- coding: utf-8 -*-
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+
+{
+    'name': 'Finland - Sale',
+    'version': '1.0',
+    'description': """Finland Sale""",
+    'category': 'Localization',
+    'depends': [
+        'l10n_fi',
+        'sale',
+    ],
+    'installable': True,
+    'application': False,
+    'auto_install': True,
+    'license': 'LGPL-3',
+}
diff --git a/addons/l10n_fi_sale/i18n/fi.po b/addons/l10n_fi_sale/i18n/fi.po
new file mode 100644
index 00000000000..4f1102ec887
--- /dev/null
+++ b/addons/l10n_fi_sale/i18n/fi.po
@@ -0,0 +1,27 @@
+# Translation of Odoo Server.
+# This file contains the translation of the following modules:
+# 	* l10n_fi_sale
+#
+msgid ""
+msgstr ""
+"Project-Id-Version: Odoo Server 13.0+e\n"
+"Report-Msgid-Bugs-To: \n"
+"POT-Creation-Date: 2022-04-04 12:50+0000\n"
+"PO-Revision-Date: 2022-04-04 12:50+0000\n"
+"Last-Translator: \n"
+"Language-Team: \n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: \n"
+"Plural-Forms: \n"
+
+#. module: l10n_fi_sale
+#: code:addons/l10n_fi_sale/models/sale.py:0
+#, python-format
+msgid "Reference must contain numeric characters"
+msgstr "Viitteen tulee sisältää numeerisia merkkejä"
+
+#. module: l10n_fi_sale
+#: model:ir.model,name:l10n_fi_sale.model_sale_order
+msgid "Sales Order"
+msgstr "Myyntitilaus"
diff --git a/addons/l10n_fi_sale/i18n/l10n_fi_sale.pot b/addons/l10n_fi_sale/i18n/l10n_fi_sale.pot
new file mode 100644
index 00000000000..1fbec349967
--- /dev/null
+++ b/addons/l10n_fi_sale/i18n/l10n_fi_sale.pot
@@ -0,0 +1,27 @@
+# Translation of Odoo Server.
+# This file contains the translation of the following modules:
+# 	* l10n_fi_sale
+#
+msgid ""
+msgstr ""
+"Project-Id-Version: Odoo Server 13.0+e\n"
+"Report-Msgid-Bugs-To: \n"
+"POT-Creation-Date: 2022-04-04 12:50+0000\n"
+"PO-Revision-Date: 2022-04-04 12:50+0000\n"
+"Last-Translator: \n"
+"Language-Team: \n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: \n"
+"Plural-Forms: \n"
+
+#. module: l10n_fi_sale
+#: code:addons/l10n_fi_sale/models/sale.py:0
+#, python-format
+msgid "Reference must contain numeric characters"
+msgstr ""
+
+#. module: l10n_fi_sale
+#: model:ir.model,name:l10n_fi_sale.model_sale_order
+msgid "Sales Order"
+msgstr ""
diff --git a/addons/l10n_fi_sale/models/__init__.py b/addons/l10n_fi_sale/models/__init__.py
new file mode 100644
index 00000000000..9bfcd2f0c87
--- /dev/null
+++ b/addons/l10n_fi_sale/models/__init__.py
@@ -0,0 +1,4 @@
+# -*- coding:utf-8 -*-
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+
+from . import sale
diff --git a/addons/l10n_fi_sale/models/sale.py b/addons/l10n_fi_sale/models/sale.py
new file mode 100644
index 00000000000..ff370b0e23e
--- /dev/null
+++ b/addons/l10n_fi_sale/models/sale.py
@@ -0,0 +1,47 @@
+# -*- coding: utf-8 -*-
+import re
+from odoo import api, models, _
+from odoo.exceptions import UserError
+
+
+class SaleOrder(models.Model):
+    _inherit = "sale.order"
+
+    def write(self, values):
+        # We compute the l10n_fi/SaleOrder.reference from itself the same way
+        # we compute the l10n_fi/AccountMove.invoice_payment_ref from its name.
+        reference = values.get('reference', False)
+        if reference:
+            values['reference'] = self.compute_payment_reference_finnish(reference)
+        return super().write(values)
+
+    @api.model
+    def number2numeric(self, number):
+        so_number = re.sub(r'\D', '', number)
+        if so_number == '' or so_number is False:
+            raise UserError(_('Reference must contain numeric characters'))
+
+        # Make sure the base number is 3...19 characters long
+        if len(so_number) < 3:
+            so_number = ('11' + so_number)[-3:]
+        elif len(so_number) > 19:
+            so_number = so_number[:19]
+
+        return so_number
+
+    @api.model
+    def get_finnish_check_digit(self, base_number):
+        # Multiply digits from end to beginning with 7, 3 and 1 and
+        # calculate the sum of the products
+        total = sum((7, 3, 1)[idx % 3] * int(val) for idx, val in
+                    enumerate(base_number[::-1]))
+        # Subtract the sum from the next decade. 10 = 0
+        return str((10 - (total % 10)) % 10)
+
+    @api.model
+    def compute_payment_reference_finnish(self, number):
+        # Drop all non-numeric characters
+        so_number = self.number2numeric(number)
+        # Calculate the Finnish check digit
+        check_digit = self.get_finnish_check_digit(so_number)
+        return so_number + check_digit
diff --git a/addons/l10n_fi_sale/static/description/icon.png b/addons/l10n_fi_sale/static/description/icon.png
new file mode 100644
index 00000000000..0d382126003
Binary files /dev/null and b/addons/l10n_fi_sale/static/description/icon.png differ