diff --git a/addons/hr_timesheet/project_timesheet.py b/addons/hr_timesheet/project_timesheet.py
index 8a50f3c1ef4..20ef3b873db 100644
--- a/addons/hr_timesheet/project_timesheet.py
+++ b/addons/hr_timesheet/project_timesheet.py
@@ -76,3 +76,18 @@ class Task(models.Model):
             vals['parent_id'] = context.pop('default_parent_id', None)
         task = super(Task, self.with_context(context)).create(vals)
         return task
+
+    @api.multi
+    def write(self, values):
+        result = super(Task, self).write(values)
+        # reassign project_id on related timesheet lines
+        if 'project_id' in values:
+            project_id = values.get('project_id')
+            # a timesheet must have an analytic account (and a project)
+            if not project_id:
+                raise UserError(_('This task must have a project since they are linked to timesheets.'))
+            self.sudo().mapped('timesheet_ids').write({
+                'project_id': project_id,
+                'account_id': self.env['project.project'].browse(project_id).sudo().analytic_account_id.id
+            })
+        return result
diff --git a/addons/hr_timesheet/tests/test_timesheet.py b/addons/hr_timesheet/tests/test_timesheet.py
index e744d4341f7..ee93d9e0905 100644
--- a/addons/hr_timesheet/tests/test_timesheet.py
+++ b/addons/hr_timesheet/tests/test_timesheet.py
@@ -2,7 +2,7 @@
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
 from odoo.tests.common import TransactionCase
-from odoo.exceptions import AccessError
+from odoo.exceptions import AccessError, UserError
 
 
 class TestTimesheet(TransactionCase):
@@ -116,3 +116,42 @@ class TestTimesheet(TransactionCase):
             'employee_id': self.empl_employee2.id,
         })
         self.assertEquals(timesheet1.user_id, self.user_employee2, 'Changing timesheet employee should change the related user')
+
+    def test_transfert_project(self):
+        """ Test transfert task with timesheet to another project """
+        Timesheet = self.env['account.analytic.line']
+        # create a second project
+        self.project_customer2 = self.env['project.project'].create({
+            'name': 'Project NUMBER DEUX',
+            'allow_timesheets': True,
+        })
+        # employee 1 log some timesheet on task 1
+        Timesheet.create({
+            'project_id': self.project_customer.id,
+            'task_id': self.task1.id,
+            'name': 'my first timesheet',
+            'unit_amount': 4,
+        })
+
+        timesheet_count1 = Timesheet.search_count([('project_id', '=', self.project_customer.id)])
+        timesheet_count2 = Timesheet.search_count([('project_id', '=', self.project_customer2.id)])
+        self.assertEquals(timesheet_count1, 1, "One timesheet in project 1")
+        self.assertEquals(timesheet_count2, 0, "No timesheet in project 2")
+        self.assertEquals(len(self.task1.timesheet_ids), 1, "The timesheet should be linked to task 1")
+
+        # change project of task 1
+        self.task1.write({
+            'project_id': self.project_customer2.id
+        })
+
+        timesheet_count1 = Timesheet.search_count([('project_id', '=', self.project_customer.id)])
+        timesheet_count2 = Timesheet.search_count([('project_id', '=', self.project_customer2.id)])
+        self.assertEquals(timesheet_count1, 0, "No timesheet in project 1")
+        self.assertEquals(timesheet_count2, 1, "One timesheet in project 2")
+        self.assertEquals(len(self.task1.timesheet_ids), 1, "The timesheet should be linked to task 1")
+
+        # it is forbidden to set a task with timesheet without project
+        with self.assertRaises(UserError):
+            self.task1.write({
+                'project_id': False
+            })