diff --git a/addons/sale_timesheet/models/sale_order.py b/addons/sale_timesheet/models/sale_order.py
index 37e2f4bf9fe..a11e320a645 100644
--- a/addons/sale_timesheet/models/sale_order.py
+++ b/addons/sale_timesheet/models/sale_order.py
@@ -67,7 +67,7 @@ class SaleOrder(models.Model):
                             order._create_analytic_account(prefix=line.product_id.default_code or None)
                         order.project_id.project_create({'name': order.project_id.name})
                         break
-            order.order_line.filtered(lambda line: line._is_task())._create_task()
+            order.order_line.filtered(lambda line: line.is_service_task)._timesheet_find_task()
         return result
 
     @api.multi
@@ -134,13 +134,19 @@ class SaleOrderLine(models.Model):
     _inherit = "sale.order.line"
 
     task_id = fields.Many2one('project.task', 'Task')
+    is_service_task = fields.Boolean("Will create a task", compute='_compute_is_service_task')
+
+    @api.multi
+    def _compute_is_service_task(self):
+        for so_line in self:
+            so_line.is_service_task = so_line.product_id.type == 'service' and so_line.product_id.track_service == 'task'
 
     @api.model
     def create(self, values):
         line = super(SaleOrderLine, self).create(values)
         if line.state == 'sale' and not line.order_id.project_id and line.product_id.track_service in ['timesheet', 'task']:
             line.order_id._create_analytic_account()
-            line._create_task()
+            line._timesheet_find_task()
         return line
 
     def _timesheet_compute_delivered_quantity_domain(self):
@@ -163,7 +169,7 @@ class SaleOrderLine(models.Model):
             planned_hours = self.product_uom_qty
         return planned_hours
 
-    def _get_project(self):
+    def _timesheet_find_project(self):
         Project = self.env['project.project']
         project = self.product_id.with_context(force_company=self.company_id.id).project_id
         if not project:
@@ -174,13 +180,13 @@ class SaleOrderLine(models.Model):
                 account = self.order_id.project_id
             project = Project.search([('analytic_account_id', '=', account.id)], limit=1)
             if not project:
-                project_id = account.project_create({'name': account.name, 'use_tasks': True})
+                project_id = account.project_create({'name': account.name})
                 project = Project.browse(project_id)
         return project
 
-    def _prepare_service_task_values(self):
+    def _timesheet_create_task_prepare_values(self):
         self.ensure_one()
-        project = self._get_project()
+        project = self._timesheet_find_project()
         planned_hours = self._convert_qty_company_hours()
         return {
             'name': '%s:%s' % (self.order_id.name or '', self.product_id.name),
@@ -193,12 +199,47 @@ class SaleOrderLine(models.Model):
             'company_id': self.company_id.id,
         }
 
-    def _create_task(self):
-        for line in self:
-            task_values = line._prepare_service_task_values()
-            task = self.env['project.task'].create(task_values)
-            self.write({'task_id': task.id})
+    @api.multi
+    def _timesheet_create_task(self):
+        """ Generate task for the given so line, and link it.
 
-    def _is_task(self):
-        self.ensure_one()
-        return self.product_id.type == 'service' and self.product_id.track_service == 'task'
+            :return a mapping with the so line id and its linked task
+            :rtype dict
+        """
+        result = {}
+        for so_line in self:
+            # create task
+            values = so_line._timesheet_create_task_prepare_values()
+            task = self.env['project.task'].sudo().create(values)
+            so_line.write({'task_id': task.id})
+            # post message on SO
+            msg_body = _("Task Created (%s): <a href=# data-oe-model=project.task data-oe-id=%d>%s</a>") % (so_line.product_id.name, task.id, task.name)
+            so_line.order_id.message_post(body=msg_body)
+            # post message on task
+            task_msg = _("This task has been created from: <a href=# data-oe-model=sale.order data-oe-id=%d>%s</a> (%s)") % (so_line.order_id.id, so_line.order_id.name, so_line.product_id.name)
+            task.message_post(body=task_msg)
+
+            result[so_line.id] = task
+        return result
+
+    @api.multi
+    def _timesheet_find_task(self):
+        """ Find the task generated by the so lines. If no task linked, it will be
+            created automatically.
+
+            :return a mapping with the so line id and its linked task
+            :rtype dict
+        """
+        # one search for all so lines
+        tasks = self.env['project.task'].search([('sale_line_id', 'in', self.ids)])
+        task_sol_mapping = {task.sale_line_id.id: task for task in tasks}
+
+        result = {}
+        for so_line in self:
+            # If the SO was confirmed, cancelled, set to draft then confirmed, avoid creating a new task.
+            task = task_sol_mapping.get(so_line.id)
+            # If not found, create one task for the so line
+            if not task:
+                task = so_line._timesheet_create_task()[so_line.id]
+            result[so_line.id] = task
+        return result