diff --git a/account_tag_category/models/account.py b/account_tag_category/models/account.py
index 5510aba84..b04cb22a0 100644
--- a/account_tag_category/models/account.py
+++ b/account_tag_category/models/account.py
@@ -11,7 +11,8 @@ class AccountAccountTag(models.Model):
     _inherit = 'account.account.tag'
 
     tag_category_id = fields.Many2one('account.account.tag.category',
-                                      'tag_ids', ondelete='set null')
+                                      string='Tag category',
+                                      ondelete='set null')
 
     category_color = fields.Integer(related='tag_category_id.color')
 
@@ -85,6 +86,10 @@ class AccountAccountTagCategory(models.Model):
                                         'the same model as this category (%s)'
                                         ) % self.applicability)
 
+    @api.multi
+    def name_get(self):
+        return [(cat.id, cat.name) for cat in self]
+
 
 class AccountAccount(models.Model):
 
diff --git a/account_tag_category/wizard/update_tags_wizard.py b/account_tag_category/wizard/update_tags_wizard.py
index acea01b68..a145c447c 100644
--- a/account_tag_category/wizard/update_tags_wizard.py
+++ b/account_tag_category/wizard/update_tags_wizard.py
@@ -2,7 +2,8 @@
 # Copyright 2017 Camptocamp SA
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
 
-from odoo import models, fields, api
+from odoo import models, fields, api, _
+from odoo.exceptions import ValidationError
 
 
 class AccountTagCategoryUpdateTags(models.TransientModel):
@@ -28,6 +29,17 @@ class AccountTagCategoryUpdateTags(models.TransientModel):
     @api.multi
     def save_tags_to_category(self):
 
+        categorized_tags = self.tag_ids.filtered(
+            lambda t: t.tag_category_id and
+            t.tag_category_id != self.tag_category_id)
+        if categorized_tags:
+            tags_error = ["- %s (%s)" % (t.name, t.tag_category_id.name)
+                          for t in categorized_tags]
+            raise ValidationError(_('Following tags are already defined on '
+                                    'another tag category : \n %s') %
+                                  "\n".join(tags_error)
+                                  )
+
         self.tag_category_id.write({
             'tag_ids': [(6, False, self.tag_ids.ids)]
         })