diff --git a/addons/hr_payroll/models/hr_benefit.py b/addons/hr_payroll/models/hr_benefit.py
index 866709f241e..74cc3db97b0 100644
--- a/addons/hr_payroll/models/hr_benefit.py
+++ b/addons/hr_payroll/models/hr_benefit.py
@@ -139,7 +139,9 @@ class HrBenefit(models.Model):
             r['employee_id'][0],
             r['benefit_type_id'][0] if r['benefit_type_id'] else False,
         ) for r in month_recs}
-        new_vals = [v for v in vals_list if (v['date_start'].replace(tzinfo=None), v['date_stop'].replace(tzinfo=None), v['employee_id'], v['benefit_type_id']) not in existing_entries]
+        assert all(v['date_start'].tzinfo is None for v in vals_list)
+        assert all(v['date_stop'].tzinfo is None for v in vals_list)
+        new_vals = [v for v in vals_list if (v['date_start'], v['date_stop'], v['employee_id'], v['benefit_type_id']) not in existing_entries]
         # Remove duplicates from vals_list, shouldn't be necessary from saas-12.2
         unique_new_vals = set()
         for values in new_vals:
@@ -184,8 +186,6 @@ class HrBenefit(models.Model):
             if benefit.date_start.date() == benefit.date_stop.date():
                 new_benefits |= benefit
             else:
-                tz = pytz.timezone(benefit.employee_id.tz)
-                benefit_start, benefit_stop = tz.localize(benefit.date_start), tz.localize(benefit.date_stop)
                 values = {
                     'name': benefit.name,
                     'employee_id': benefit.employee_id.id,
@@ -193,9 +193,9 @@ class HrBenefit(models.Model):
                 }
                 benefit_state = benefit.state
                 benefits_to_unlink |= benefit
-                for start, stop in _split_range_by_day(benefit_start, benefit_stop):
-                    values['date_start'] = start.astimezone(pytz.utc)
-                    values['date_stop'] = stop.astimezone(pytz.utc)
+                for start, stop in _split_range_by_day(benefit.date_start, benefit.date_stop):
+                    values['date_start'] = start
+                    values['date_stop'] = stop
                     new_benefit = self.create(values)
                     # Write the state after the creation due to the ir.rule on benefit state
                     new_benefit.state = benefit_state
@@ -244,8 +244,8 @@ class HrBenefit(models.Model):
     def _duplicate_to_calendar_attendance(self):
         mapped_data = {
             benefit: [
-                pytz.utc.localize(benefit.date_start).astimezone(pytz.timezone(benefit.employee_id.tz)), # Start date
-                pytz.utc.localize(benefit.date_stop).astimezone(pytz.timezone(benefit.employee_id.tz)) # End date
+                benefit.date_start,
+                benefit.date_stop,
             ] for benefit in self
         }
 
diff --git a/addons/hr_payroll/models/hr_employee.py b/addons/hr_payroll/models/hr_employee.py
index cbcbb0d8820..54a8edc235e 100644
--- a/addons/hr_payroll/models/hr_employee.py
+++ b/addons/hr_payroll/models/hr_employee.py
@@ -1,11 +1,11 @@
 # -*- coding:utf-8 -*-
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
-from odoo import api, fields, models, _
-from odoo.addons.resource.models.resource import Intervals
-from datetime import datetime, timedelta
+from datetime import datetime
 import pytz
 
+from odoo import api, fields, models
+
 
 class HrEmployee(models.Model):
     _inherit = 'hr.employee'
@@ -22,20 +22,18 @@ class HrEmployee(models.Model):
 
     @api.multi
     def generate_benefit(self, date_start, date_stop):
-        date_start = date_start.replace(tzinfo=pytz.utc)
-        date_stop = date_stop.replace(tzinfo=pytz.utc)
+        date_start = fields.Datetime.to_datetime(date_start)
+        date_stop = fields.Datetime.to_datetime(date_stop)
         attendance_type = self.env.ref('hr_payroll.benefit_type_attendance')
         vals_list = []
-        leaves = self.env['hr.leave']
 
         for employee in self:
-
             # Approved leaves
             emp_leaves = employee.resource_calendar_id.leave_ids.filtered(
                 lambda r:
                     r.resource_id == employee.resource_id and
-                    r.date_from.replace(tzinfo=pytz.utc) <= date_stop and
-                    r.date_to.replace(tzinfo=pytz.utc) >= date_start
+                    r.date_from <= date_stop and
+                    r.date_to >= date_start
                 )
             global_leaves = employee.resource_calendar_id.global_leave_ids
 
@@ -43,9 +41,8 @@ class HrEmployee(models.Model):
             vals_list.extend(employee_leaves._get_benefits_values())
 
             for contract in employee._get_contracts(date_start, date_stop):
-
-                date_start_benefits = max(date_start, datetime.combine(contract.date_start, datetime.min.time()).replace(tzinfo=pytz.utc))
-                date_stop_benefits = min(date_stop, datetime.combine(contract.date_end or datetime.max.date(), datetime.max.time()).replace(tzinfo=pytz.utc))
+                date_start_benefits = max(date_start, fields.Datetime.to_datetime(contract.date_start)).replace(tzinfo=pytz.utc)
+                date_stop_benefits = min(date_stop, datetime.combine(contract.date_end or datetime.max.date(), datetime.max.time())).replace(tzinfo=pytz.utc)
 
                 calendar = contract.resource_calendar_id
                 resource = employee.resource_id
@@ -53,10 +50,11 @@ class HrEmployee(models.Model):
                 # Attendances
                 for interval in attendances:
                     benefit_type_id = interval[2].mapped('benefit_type_id')[:1] or attendance_type
+                    # All benefits generated here are using datetimes converted from the employee's timezone
                     vals_list += [{
                         'name': "%s: %s" % (benefit_type_id.name, employee.name),
-                        'date_start': interval[0].astimezone(pytz.utc),
-                        'date_stop': interval[1].astimezone(pytz.utc),
+                        'date_start': interval[0].astimezone(pytz.utc).replace(tzinfo=None),
+                        'date_stop': interval[1].astimezone(pytz.utc).replace(tzinfo=None),
                         'benefit_type_id': benefit_type_id.id,
                         'employee_id': employee.id,
                         'state': 'confirmed',
diff --git a/addons/hr_payroll/tests/test_benefit.py b/addons/hr_payroll/tests/test_benefit.py
index ec1b4c25248..e80f7266c63 100644
--- a/addons/hr_payroll/tests/test_benefit.py
+++ b/addons/hr_payroll/tests/test_benefit.py
@@ -2,9 +2,9 @@
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
 from datetime import datetime
-import pytz
 from dateutil.relativedelta import relativedelta
-from odoo import exceptions
+import pytz
+
 from odoo.fields import Datetime, Date
 from odoo.tests.common import tagged
 from odoo.addons.hr_payroll.tests.common import TestPayslipBase
@@ -12,15 +12,14 @@ from odoo.addons.hr_payroll.tests.common import TestPayslipBase
 
 @tagged('benefit')
 class TestBenefit(TestPayslipBase):
-
     def setUp(self):
         super(TestBenefit, self).setUp()
         self.tz = pytz.timezone(self.richard_emp.tz)
-        self.start = self.to_datetime_tz('2015-11-01 01:00:00')
-        self.end = self.to_datetime_tz('2015-11-30 23:59:59')
+        self.start = datetime(2015, 11, 1, 1, 0, 0)
+        self.end = datetime(2015, 11, 30, 23, 59, 59)
         self.resource_calendar_id = self.env['resource.calendar'].create({'name': 'Zboub'})
         self.env['hr.contract'].create({
-            'date_start': self.start - relativedelta(days=5),
+            'date_start': self.start.date() - relativedelta(days=5),
             'name': 'dodo',
             'resource_calendar_id': self.resource_calendar_id.id,
             'wage': 1000,
@@ -47,24 +46,6 @@ class TestBenefit(TestPayslipBase):
             'code': 'WORK200'
         })
 
-    def to_datetime_tz(self, datetime_str, tz=None):
-        tz = tz or self.tz
-        return tz.localize(Datetime.to_datetime(datetime_str))
-
-    def assertDatetimeTzEqual(self, value, target, tz=None):
-        """
-        Assert equality between two dates.
-        :param value: timezone naive datetime
-        :param target: datetime string
-        :param tz: timezone to interpret the tartget string
-        :raises AssertionError: raises exception if the two dates are not equal
-        """
-        tz = tz or self.tz
-        self.assertEqual(
-            pytz.utc.localize(value).astimezone(tz),
-            self.to_datetime_tz(target, tz=tz)
-        )
-
     def test_no_duplicate(self):
         self.richard_emp.generate_benefit(self.start, self.end)
         pou1 = self.env['hr.benefit'].search_count([])
@@ -73,16 +54,14 @@ class TestBenefit(TestPayslipBase):
         self.assertEqual(pou1, pou2, "Benefits should not be duplicated")
 
     def test_benefit(self):
-
         self.richard_emp.generate_benefit(self.start, self.end)
-
-        attendance_nb = len(self.resource_calendar_id._attendance_intervals(self.start, self.end))
+        attendance_nb = len(self.resource_calendar_id._attendance_intervals(self.start.replace(tzinfo=pytz.utc), self.end.replace(tzinfo=pytz.utc)))
         benefit_nb = self.env['hr.benefit'].search_count([('employee_id', '=', self.richard_emp.id)])
         self.assertEqual(attendance_nb, benefit_nb, "One benefit should be generated for each calendar attendance")
 
     def test_split_benefit_by_day(self):
-        start = self.to_datetime_tz('2015-11-01 09:00:00')
-        end = self.to_datetime_tz('2015-11-03 18:00:00')
+        start = datetime(2015, 11, 1, 9, 0, 0)
+        end = datetime(2015, 11, 3, 18, 0, 0)
 
         # Benefit of type attendance should be split in three
         benefit = self.env['hr.benefit'].create({
@@ -95,18 +74,18 @@ class TestBenefit(TestPayslipBase):
         benefits = benefit._split_by_day()
         self.assertEqual(len(benefits), 3, "Benefit should be split in three")
 
-        self.assertDatetimeTzEqual(benefits[0].date_start, '2015-11-01 09:00:00')
-        self.assertDatetimeTzEqual(benefits[0].date_stop, '2015-11-01 23:59:59')
+        self.assertEqual(benefits[0].date_start, datetime(2015, 11, 1, 9, 0, 0))
+        self.assertEqual(benefits[0].date_stop, datetime(2015, 11, 1, 23, 59, 59))
 
-        self.assertDatetimeTzEqual(benefits[1].date_start, '2015-11-02 00:00:00')
-        self.assertDatetimeTzEqual(benefits[1].date_stop, '2015-11-02 23:59:59')
+        self.assertEqual(benefits[1].date_start, datetime(2015, 11, 2, 0, 0, 0))
+        self.assertEqual(benefits[1].date_stop, datetime(2015, 11, 2, 23, 59, 59))
 
-        self.assertDatetimeTzEqual(benefits[2].date_start, '2015-11-03 00:00:00')
-        self.assertDatetimeTzEqual(benefits[2].date_stop, '2015-11-03 18:00:00')
+        self.assertEqual(benefits[2].date_start, datetime(2015, 11, 3, 0, 0, 0))
+        self.assertEqual(benefits[2].date_stop, datetime(2015, 11, 3, 18, 0, 0))
 
         # Test with end at mid-night -> should not create benefit starting and ending at the same time (at 00:00)
-        start = self.to_datetime_tz('2013-11-01 00:00:00')
-        end = self.to_datetime_tz('2013-11-04 00:00:00')
+        start = datetime(2013, 11, 1, 0, 0, 0)
+        end = datetime(2013, 11, 4, 0, 0, 0)
 
         benefit = self.env['hr.benefit'].create({
             'name': '1',
@@ -116,19 +95,18 @@ class TestBenefit(TestPayslipBase):
         })
         benefits = benefit._split_by_day()
         self.assertEqual(len(benefits), 3, "Benefit should be split in three")
-        self.assertDatetimeTzEqual(benefits[0].date_start, '2013-11-01 00:00:00')
-        self.assertDatetimeTzEqual(benefits[0].date_stop, '2013-11-01 23:59:59')
+        self.assertEqual(benefits[0].date_start, datetime(2013, 11, 1, 0, 0, 0))
+        self.assertEqual(benefits[0].date_stop, datetime(2013, 11, 1, 23, 59, 59))
 
-        self.assertDatetimeTzEqual(benefits[1].date_start, '2013-11-02 00:00:00')
-        self.assertDatetimeTzEqual(benefits[1].date_stop, '2013-11-02 23:59:59')
+        self.assertEqual(benefits[1].date_start, datetime(2013, 11, 2, 0, 0, 0))
+        self.assertEqual(benefits[1].date_stop, datetime(2013, 11, 2, 23, 59, 59))
 
-        self.assertDatetimeTzEqual(benefits[2].date_start, '2013-11-03 00:00:00')
-        self.assertDatetimeTzEqual(benefits[2].date_stop, '2013-11-03 23:59:59')
+        self.assertEqual(benefits[2].date_start, datetime(2013, 11, 3, 0, 0, 0))
+        self.assertEqual(benefits[2].date_stop, datetime(2013, 11, 3, 23, 59, 59))
 
     def test_approve_multiple_day_benefit(self):
-
-        start = self.to_datetime_tz('2015-11-01 09:00:00')
-        end = self.to_datetime_tz('2015-11-03 18:00:00')
+        start = datetime(2015, 11, 1, 9, 0, 0)
+        end = datetime(2015, 11, 3, 18, 0, 0)
 
         # Benefit of type attendance should be split in three
         benefit = self.env['hr.benefit'].create({
@@ -144,8 +122,8 @@ class TestBenefit(TestPayslipBase):
         self.assertEqual(len(benefits), 3, "Benefit should be split in three")
 
     def test_duplicate_global_benefit_to_attendance(self):
-        start = self.to_datetime_tz('2015-11-01 09:00:00')
-        end = self.to_datetime_tz('2015-11-03 18:00:00')
+        start = datetime(2015, 11, 1, 9, 0, 0)
+        end = datetime(2015, 11, 3, 18, 0, 0)
 
         benef = self.env['hr.benefit'].create({
             'name': '1',
@@ -162,8 +140,8 @@ class TestBenefit(TestPayslipBase):
         self.assertEqual(attendance_nb, 0, "It should not duplicate the 'normal/global' benefit type")
 
     def test_duplicate_benefit_to_attendance(self):
-        start = self.to_datetime_tz('2015-11-01 09:00:00')
-        end = self.to_datetime_tz('2015-11-03 18:00:00')
+        start = datetime(2015, 11, 1, 9, 0, 0)
+        end = datetime(2015, 11, 3, 18, 0, 0)
 
         # Benefit (not leave) should be split in three attendance
         benef = self.env['hr.benefit'].create({
@@ -199,8 +177,8 @@ class TestBenefit(TestPayslipBase):
         ]))
 
     def test_create_benefit_leave(self):
-        start = self.to_datetime_tz('2015-11-01 09:00:00')
-        end = self.to_datetime_tz('2015-11-03 18:00:00')
+        start = datetime(2015, 11, 1, 9, 0, 0)
+        end = datetime(2015, 11, 3, 18, 0, 0)
 
         benef = self.env['hr.benefit'].create({
             'name': 'Richard leave from benef',
@@ -215,8 +193,8 @@ class TestBenefit(TestPayslipBase):
         self.assertEqual(calendar_leave.benefit_type_id, benef.benefit_type_id, "It should have the same benefit type")
 
     def test_validate_conflict_benefit(self):
-        start = self.to_datetime_tz('2015-11-01 09:00:00')
-        end = self.to_datetime_tz('2015-11-01 13:00:00')
+        start = datetime(2015, 11, 1, 9, 0, 0)
+        end = datetime(2015, 11, 1, 13, 0, 0)
         benef1 = self.env['hr.benefit'].create({
             'name': '1',
             'employee_id': self.richard_emp.id,
@@ -224,7 +202,7 @@ class TestBenefit(TestPayslipBase):
             'date_start': start,
             'date_stop': end + relativedelta(hours=5),
         })
-        benef2 = self.env['hr.benefit'].create({
+        self.env['hr.benefit'].create({
             'name': '2',
             'employee_id': self.richard_emp.id,
             'benefit_type_id': self.env.ref('hr_payroll.benefit_type_attendance').id,
@@ -243,7 +221,7 @@ class TestBenefit(TestPayslipBase):
             'date_start': self.start,
             'date_stop': self.end,
         })
-        leave_1 = self.env['hr.leave'].create({
+        self.env['hr.leave'].create({
             'name': 'Doctor Appointment',
             'employee_id': self.richard_emp.id,
             'holiday_status_id': self.leave_type.id,
@@ -251,7 +229,7 @@ class TestBenefit(TestPayslipBase):
             'date_to': self.start + relativedelta(days=1),
             'number_of_days': 2,
         })
-        self.assertFalse(benef1.action_validate(benef1.ids),"It should not validate benefits conflicting with non approved leaves")
+        self.assertFalse(benef1.action_validate(benef1.ids), "It should not validate benefits conflicting with non approved leaves")
         self.assertTrue(benef1.display_warning)
 
     def test_validate_undefined_benefit(self):
@@ -261,11 +239,11 @@ class TestBenefit(TestPayslipBase):
             'date_start': self.start,
             'date_stop': self.end,
         })
-        self.assertFalse(benef1.action_validate(benef1.ids),"It should not validate benefits without a type")
+        self.assertFalse(benef1.action_validate(benef1.ids), "It should not validate benefits without a type")
 
     def test_approve_leave_benefit(self):
-        start = self.to_datetime_tz('2015-11-01 09:00:00')
-        end = self.to_datetime_tz('2015-11-03 13:00:00')
+        start = datetime(2015, 11, 1, 9, 0, 0)
+        end = datetime(2015, 11, 3, 13, 0, 0)
         leave = self.env['hr.leave'].create({
             'name': 'Doctor Appointment',
             'employee_id': self.richard_emp.id,
@@ -285,13 +263,13 @@ class TestBenefit(TestPayslipBase):
         leave.action_approve()
 
         new_leave_benef = self.env['hr.benefit'].search([
-            ('date_start', '=', Datetime.to_datetime('2015-11-01 09:00:00')),
-            ('date_stop', '=', Datetime.to_datetime('2015-11-02 09:00:00')),
+            ('date_start', '=', Datetime.to_datetime(datetime(2015, 11, 1, 9, 0, 0))),
+            ('date_stop', '=', Datetime.to_datetime(datetime(2015, 11, 2, 9, 0, 0))),
             ('benefit_type_id.is_leave', '=', True)
         ])
 
         new_benef = self.env['hr.benefit'].search([
-            ('date_start', '=', Datetime.to_datetime('2015-11-02 09:00:01')),
+            ('date_start', '=', Datetime.to_datetime(datetime(2015, 11, 2, 9, 0, 1))),
             ('date_stop', '=', end),
             ('benefit_type_id.is_leave', '=', False)
         ])
@@ -302,8 +280,8 @@ class TestBenefit(TestPayslipBase):
         self.assertTrue(benef.action_validate((new_benef | new_leave_benef).ids), "It should be able to validate the benefits")
 
     def test_refuse_leave_benefit(self):
-        start = self.to_datetime_tz('2015-11-01 09:00:00')
-        end = self.to_datetime_tz('2015-11-03 13:00:00')
+        start = datetime(2015, 11, 1, 9, 0, 0)
+        end = datetime(2015, 11, 3, 13, 0, 0)
         leave = self.env['hr.leave'].create({
             'name': 'Doctor Appointment',
             'employee_id': self.richard_emp.id,
@@ -331,8 +309,8 @@ class TestBenefit(TestPayslipBase):
         self.assertEqual(data['hours'], 168.0)
 
     def test_time_extra_benefit(self):
-        start = self.to_datetime_tz('2015-11-01 10:00:00')
-        end = self.to_datetime_tz('2015-11-01 17:00:00')
+        start = datetime(2015, 11, 1, 10, 0, 0)
+        end = datetime(2015, 11, 1, 17, 0, 0)
         benef = self.env['hr.benefit'].create({
             'name': '1',
             'employee_id': self.richard_emp.id,
@@ -346,8 +324,8 @@ class TestBenefit(TestPayslipBase):
 
     def test_time_week_leave_benefit(self):
         # /!\ this is a week day => it exists an calendar attendance at this time
-        start = self.to_datetime_tz('2015-11-02 10:00:00', tz=pytz.utc)
-        end = self.to_datetime_tz('2015-11-02 17:00:00', tz=pytz.utc)
+        start = datetime(2015, 11, 2, 10, 0, 0)
+        end = datetime(2015, 11, 2, 17, 0, 0)
         leave_benef = self.env['hr.benefit'].create({
             'name': '1leave',
             'employee_id': self.richard_emp.id,
@@ -361,8 +339,8 @@ class TestBenefit(TestPayslipBase):
 
     def test_time_weekend_leave_benefit(self):
         # /!\ this is in the weekend => no calendar attendance at this time
-        start = self.to_datetime_tz('2015-11-01 10:00:00', tz=pytz.utc)
-        end = self.to_datetime_tz('2015-11-01 17:00:00', tz=pytz.utc)
+        start = datetime(2015, 11, 1, 10, 0, 0)
+        end = datetime(2015, 11, 1, 17, 0, 0)
         leave_benef = self.env['hr.benefit'].create({
             'name': '1leave',
             'employee_id': self.richard_emp.id,
@@ -376,8 +354,8 @@ class TestBenefit(TestPayslipBase):
 
     def test_payslip_generation_with_leave(self):
         # /!\ this is a week day => it exists an calendar attendance at this time
-        start = self.to_datetime_tz('2015-11-02 10:00:00', tz=pytz.utc)
-        end = self.to_datetime_tz('2015-11-02 17:00:00', tz=pytz.utc)
+        start = datetime(2015, 11, 2, 10, 0, 0)
+        end = datetime(2015, 11, 2, 17, 0, 0)
         leave_benef = self.env['hr.benefit'].create({
             'name': '1leave',
             'employee_id': self.richard_emp.id,
@@ -399,8 +377,8 @@ class TestBenefit(TestPayslipBase):
 
     def test_payslip_generation_with_extra_work(self):
         # /!\ this is in the weekend (Sunday) => no calendar attendance at this time
-        start = self.to_datetime_tz('2015-11-01 10:00:00', tz=pytz.utc)
-        end = self.to_datetime_tz('2015-11-01 17:00:00', tz=pytz.utc)
+        start = datetime(2015, 11, 1, 10, 0, 0)
+        end = datetime(2015, 11, 1, 17, 0, 0)
         benef = self.env['hr.benefit'].create({
             'name': 'Extra',
             'employee_id': self.richard_emp.id,