diff --git a/crm_lead_vat/models/crm_lead.py b/crm_lead_vat/models/crm_lead.py
index d117a688622..988a86fb676 100644
--- a/crm_lead_vat/models/crm_lead.py
+++ b/crm_lead_vat/models/crm_lead.py
@@ -1,7 +1,7 @@
 # Copyright 2015 Antiun Ingeniería, S.L.
 # License AGPL-3.0 or later (https://www.gnu.org/licenses/agpl.html).
 
-from odoo import fields, models
+from odoo import api, fields, models
 
 
 class Lead(models.Model):
@@ -11,11 +11,68 @@ class Lead(models.Model):
         string="TIN",
         help="Tax Identification Number. The first 2 characters are the "
         "country code.",
+        compute="_compute_vat",
+        inverse="_inverse_vat",
+        readonly=False,
+        store=True,
     )
+    partner_vat_update = fields.Boolean(
+        "Partner VAT will Update", compute="_compute_partner_vat_update"
+    )
+
+    @api.depends("partner_id.vat", "partner_id.commercial_partner_id.vat")
+    def _compute_vat(self):
+        for lead in self:
+            if (
+                lead.partner_id.commercial_partner_id.vat
+                and lead._get_partner_vat_update()
+            ):
+                lead.vat = lead.partner_id.commercial_partner_id.vat
+            elif lead.partner_id.vat and lead._get_partner_vat_update():
+                lead.vat = lead.partner_id.vat
+
+    def _inverse_vat(self):
+        for lead in self:
+            if lead._get_partner_vat_update():
+                if lead.partner_id.commercial_partner_id:
+                    lead.partner_id.commercial_partner_id.vat = lead.vat
+                else:
+                    lead.partner_id.vat = lead.vat
+
+    @api.depends("vat", "partner_id")
+    def _compute_partner_vat_update(self):
+        for lead in self:
+            lead.partner_vat_update = lead._get_partner_vat_update()
+
+    def _get_partner_vat_update(self):
+        """Calculate if we should write the vat on the related partner. When
+        the vat of the lead / partner is an empty string, we force it to False
+        to not propagate a False on an empty string.
+
+        Done in a separate method so it can be used in both ribbon and inverse
+        and compute of vat update methods.
+        """
+        self.ensure_one()
+        if (
+            self.partner_id.commercial_partner_id
+            and self.vat != self.partner_id.commercial_partner_id.vat
+        ):
+            return self.vat != self.partner_id.commercial_partner_id.vat
+        elif self.partner_id and self.vat != self.partner_id.vat:
+            return self.vat != self.partner_id.vat
+        return False
 
-    def _create_customer(self):
+    def _prepare_customer_values(self, partner_name, is_company=False, parent_id=False):
         """Add VAT to partner."""
-        return super(Lead, self.with_context(default_vat=self.vat))._create_customer()
+        res = super(Lead, self)._prepare_customer_values(
+            partner_name, is_company, parent_id
+        )
+        res.update(
+            {
+                "vat": self.vat,
+            }
+        )
+        return res
 
     def _prepare_values_from_partner(self, partner):
         """Recover VAT from partner if available."""
diff --git a/crm_lead_vat/readme/CONTRIBUTORS.rst b/crm_lead_vat/readme/CONTRIBUTORS.rst
index 2f3bb28bc81..42a50e801fb 100644
--- a/crm_lead_vat/readme/CONTRIBUTORS.rst
+++ b/crm_lead_vat/readme/CONTRIBUTORS.rst
@@ -5,3 +5,5 @@
 * `Tecnativa <https://www.tecnativa.com>`_:
 
   * Stefan Ungureanu
+
+* Emilio Pascual (`Moduon <https://www.moduon.team/>`__)
diff --git a/crm_lead_vat/readme/USAGE.rst b/crm_lead_vat/readme/USAGE.rst
index ad131e83519..f2c935f8ad5 100644
--- a/crm_lead_vat/readme/USAGE.rst
+++ b/crm_lead_vat/readme/USAGE.rst
@@ -3,3 +3,5 @@ To use this module, you need to:
 * Go to *CRM > Leads*.
 * Open a lead.
 * You will see the new field.
+* If you change vat in partner, it change in lead.
+* If you change vat in lead, a warning will show informing you that if you save, vat change in partner.
diff --git a/crm_lead_vat/tests/test_lead.py b/crm_lead_vat/tests/test_lead.py
index 2b0a3d04b5b..eb8af085f4f 100644
--- a/crm_lead_vat/tests/test_lead.py
+++ b/crm_lead_vat/tests/test_lead.py
@@ -12,6 +12,7 @@ def setUp(self):
         )
         self.partner = self.env["res.partner"].create({"name": __file__})
         self.test_field = "ES98765432M"
+        self.test2_field = "11111111H"
 
     def test_transfered_values(self):
         """Field gets transfered when creating partner."""
@@ -27,3 +28,11 @@ def test_onchange_partner_id(self):
         self.lead.partner_id = self.partner
         result = self.lead._prepare_values_from_partner(self.lead.partner_id)
         self.assertEqual(result["vat"], self.test_field)
+
+    def test_onchange_vat(self):
+        """First change vat in partner, after it change in lead"""
+        self.lead.partner_id = self.partner
+        self.partner.vat = self.test_field
+        self.assertEqual(self.partner.vat, self.lead.vat)
+        self.lead.vat = self.test2_field
+        self.assertEqual(self.partner.vat, self.lead.vat)
diff --git a/crm_lead_vat/views/crm_lead_views.xml b/crm_lead_vat/views/crm_lead_views.xml
index 43b5a9f83a7..119c1ca7395 100644
--- a/crm_lead_vat/views/crm_lead_views.xml
+++ b/crm_lead_vat/views/crm_lead_views.xml
@@ -4,11 +4,35 @@
         <field name="model">crm.lead</field>
         <field name="inherit_id" ref="crm.crm_lead_view_form" />
         <field name="arch" type="xml">
-            <xpath expr="//group/group[1]/field[@name='partner_id']" position="after">
-                <field name="vat" />
+            <xpath
+                expr="//group/group[@name='lead_partner']/field[@name='partner_id']"
+                position="after"
+            >
+                <label for="vat" class="oe_inline" />
+                <div class="o_row o_row_readonly">
+                    <field name="partner_vat_update" invisible="1" />
+                    <field name="vat" />
+                    <span
+                        class="fa fa-exclamation-triangle text-warning oe_edit_only"
+                        title="By saving this change, the customer vat number will also be updated."
+                        attrs="{'invisible': [('partner_vat_update', '=', False)]}"
+                    />
+                </div>
             </xpath>
-            <xpath expr="//group/group[2]/field[@name='partner_id']" position="after">
-                <field name="vat" />
+            <xpath
+                expr="//group/group[@name='opportunity_partner']/field[@name='partner_id']"
+                position="after"
+            >
+                <label for="vat" class="oe_inline" />
+                <div class="o_row o_row_readonly">
+                    <field name="partner_vat_update" invisible="1" />
+                    <field name="vat" />
+                    <span
+                        class="fa fa-exclamation-triangle text-warning oe_edit_only"
+                        title="By saving this change, the customer vat number will also be updated."
+                        attrs="{'invisible': [('partner_vat_update', '=', False)]}"
+                    />
+                </div>
             </xpath>
         </field>
     </record>