diff --git a/pms/models/pms_reservation.py b/pms/models/pms_reservation.py
index d844c7c7fc..42caeea24c 100644
--- a/pms/models/pms_reservation.py
+++ b/pms/models/pms_reservation.py
@@ -940,7 +940,6 @@ def _compute_reservation_line_ids(self):
             else:
                 if not reservation.reservation_line_ids:
                     reservation.reservation_line_ids = False
-            reservation.check_in_out_dates()
 
     @api.depends("board_service_room_id", "adults", "children")
     def _compute_board_service_ids(self):
@@ -1199,7 +1198,6 @@ def _compute_checkin(self):
                     record.checkin = record.folio_id.reservation_ids[0].checkin
                 else:
                     record.checkin = fields.date.today()
-            record.check_in_out_dates()
 
     @api.depends("reservation_line_ids", "checkin")
     def _compute_checkout(self):
@@ -1218,13 +1216,11 @@ def _compute_checkout(self):
             # default checkout if checkin is set
             elif record.checkin and not record.checkout:
                 if len(record.folio_id.reservation_ids) > 1:
-                    record.checkin = record.folio_id.reservation_ids[0].checkout
+                    record.checkout = record.folio_id.reservation_ids[0].checkout
                 else:
                     record.checkout = record.checkin + datetime.timedelta(days=1)
             elif not record.checkout:
                 record.checkout = False
-            # date checking
-            record.check_in_out_dates()
 
     # pylint: disable=W8110
     def _compute_precheckin_url(self):
@@ -1767,6 +1763,7 @@ def _get_default_sale_channel_origin(self):
             sale_channel_origin_id = folio.sale_channel_origin_id
         return sale_channel_origin_id
 
+    @api.constrains("checkin", "checkout")
     def check_in_out_dates(self):
         """
         1.-When date_order is less then checkin date or
@@ -1797,6 +1794,10 @@ def checkin_checkout_consecutive_dates(self):
         of the set of ordinal dates is one more than the length of the set
         """
         for record in self:
+            if not record.reservation_line_ids:
+                # an inconsistent checkin/checkout pair builds no lines at all;
+                # check_in_out_dates is the one reporting it
+                continue
             if min(record.reservation_line_ids.mapped("date")) != record.checkin:
                 raise UserError(
                     _(
diff --git a/pms/tests/test_pms_reservation.py b/pms/tests/test_pms_reservation.py
index 3c19df3131..5fcb297d97 100644
--- a/pms/tests/test_pms_reservation.py
+++ b/pms/tests/test_pms_reservation.py
@@ -231,6 +231,90 @@ def test_reservation_dates_compute_checkin_out(self):
             not correspond to the last day indicated in the dates",
         )
 
+    @freeze_time("2012-01-14")
+    def test_reservation_default_dates_from_folio(self):
+        """
+        Check the dates defaulted to a reservation added to a folio that
+        already holds one.
+        ----------------
+        A reservation created with neither dates nor reservation lines takes
+        them from the first reservation of its folio, so both stays run in
+        parallel. The checkout was being written on the checkin field, leaving
+        the new reservation without a checkout of its own.
+        """
+        # ARRANGE
+        checkin = fields.date.today() + datetime.timedelta(days=8)
+        checkout = checkin + datetime.timedelta(days=2)
+        folio = self.env["pms.folio"].create(
+            {
+                "pms_property_id": self.pms_property1.id,
+                "partner_id": self.partner1.id,
+                "sale_channel_origin_id": self.sale_channel_direct.id,
+            }
+        )
+        self.env["pms.reservation"].create(
+            {
+                "checkin": checkin,
+                "checkout": checkout,
+                "room_type_id": self.room_type_double.id,
+                "partner_id": self.partner1.id,
+                "pms_property_id": self.pms_property1.id,
+                "folio_id": folio.id,
+                "sale_channel_origin_id": self.sale_channel_direct.id,
+            }
+        )
+
+        # ACT
+        reservation = self.env["pms.reservation"].create(
+            {
+                "room_type_id": self.room_type_double.id,
+                "partner_id": self.partner1.id,
+                "pms_property_id": self.pms_property1.id,
+                "folio_id": folio.id,
+                "sale_channel_origin_id": self.sale_channel_direct.id,
+            }
+        )
+
+        # ASSERT
+        self.assertEqual(
+            reservation.checkin,
+            checkin,
+            "The reservation should start the day the folio does",
+        )
+        self.assertEqual(
+            reservation.checkout,
+            checkout,
+            "The reservation should end the day the folio does",
+        )
+
+    @freeze_time("2012-01-14")
+    def test_reservation_checkout_before_checkin(self):
+        """
+        Check that a reservation cannot end before it starts.
+        ----------------
+        The dates are validated by a constraint, so the pair is checked once
+        both of them have been computed.
+        """
+        # ARRANGE
+        checkin = fields.date.today() + datetime.timedelta(days=8)
+
+        # ACT & ASSERT
+        with self.assertRaises(
+            UserError,
+            msg="Error, it has been allowed to create a reservation ending "
+            "before it starts",
+        ):
+            self.env["pms.reservation"].create(
+                {
+                    "checkin": checkin,
+                    "checkout": checkin - datetime.timedelta(days=1),
+                    "room_type_id": self.room_type_double.id,
+                    "partner_id": self.partner1.id,
+                    "pms_property_id": self.pms_property1.id,
+                    "sale_channel_origin_id": self.sale_channel_direct.id,
+                }
+            )
+
     @freeze_time("2012-01-14")
     def test_create_reservation_start_date(self):
         """