diff --git a/addons/project/models/project.py b/addons/project/models/project.py
index 047501d2de0..2384217ffcc 100644
--- a/addons/project/models/project.py
+++ b/addons/project/models/project.py
@@ -2652,6 +2652,12 @@ class ProjectTags(models.Model):
             ['|', ('task_ids.project_id', '=', project_id), ('project_ids', 'in', project_id)]))
         return expression.AND([domain, [('id', 'in', tag_ids)]])
 
+    @api.model
+    def read_group(self, domain, fields, groupby, offset=0, limit=None, orderby=False, lazy=True):
+        if 'project_id' in self.env.context:
+            domain = self._get_project_tags_domain(domain, self.env.context.get('project_id'))
+        return super().read_group(domain, fields, groupby, offset=offset, limit=limit, orderby=orderby, lazy=lazy)
+
     @api.model
     def search_read(self, domain=None, fields=None, offset=0, limit=None, order=None):
         if 'project_id' in self.env.context: