diff --git a/cl_sii/rtc/data_models.py b/cl_sii/rtc/data_models.py
index bb5241b2..fd7c03e9 100644
--- a/cl_sii/rtc/data_models.py
+++ b/cl_sii/rtc/data_models.py
@@ -47,6 +47,23 @@ def validate_cesion_seq(value: int) -> None:
         raise ValueError("Value is out of the valid range.", value)
 
 
+def validate_cesion_fecha(value: datetime, tz: tz_utils.PytzTimezone) -> None:
+    """
+    Validate value of date and time when the "cesión" happened.
+
+    :raises ValueError:
+    """
+
+    tz_utils.validate_dt_tz(value, tz)
+
+    now_tz_aware = tz_utils.get_now_tz_aware()
+
+    if not (value.date() <= now_tz_aware.date()):
+        raise ValueError(
+            'Value of "fecha_cesion_dt" must be before or equal to the current day.', value
+        )
+
+
 def validate_cesion_monto(value: int) -> None:
     """
     Validate amount of the "cesión".
@@ -245,9 +262,9 @@ def validate_dte_tipo_dte(cls, v: object) -> object:
         return v
 
     @pydantic.validator('fecha_cesion_dt')
-    def validate_datetime_tz(cls, v: object) -> object:
+    def validate_fecha_cesion_dt(cls, v: object) -> object:
         if isinstance(v, datetime):
-            tz_utils.validate_dt_tz(v, cls.DATETIME_FIELDS_TZ)
+            validate_cesion_fecha(v, cls.DATETIME_FIELDS_TZ)
         return v
 
     @pydantic.validator('fecha_cesion_dt')
@@ -321,6 +338,9 @@ class CesionL0:
         - Same timestamp as the "Registro AoR DTE" event ``DTE Cedido``.
         - The above statements were empirically verified for
           ``CesionNaturalKey(dte_key=DteNaturalKey(Rut('99***140-4'), 33, 3105), seq=2)``.
+        - When receiving an XML AEC document, the SII validates this date is before or
+          equal to the current day.
+          Source: (https://www.sii.cl/factura_electronica/ins_tecnico.pdf)
 
     .. warning:: The timestamp is generated by the signer of the AEC so it
         cannot be fully trusted. It is not clear how much validation is
@@ -392,9 +412,9 @@ def validate_seq(cls, v: object) -> object:
         return v
 
     @pydantic.validator('fecha_cesion_dt')
-    def validate_datetime_tz(cls, v: object) -> object:
+    def validate_fecha_cesion_dt(cls, v: object) -> object:
         if isinstance(v, datetime):
-            tz_utils.validate_dt_tz(v, cls.DATETIME_FIELDS_TZ)
+            validate_cesion_fecha(v, cls.DATETIME_FIELDS_TZ)
         return v
 
 
@@ -676,10 +696,13 @@ def as_dte_data_l2(self) -> dte_data_models.DteDataL2:
 
     # TODO: Validate value of 'fecha_ultimo_vencimiento' in relation to the DTE data.
 
-    @pydantic.validator(
-        'fecha_cesion_dt',
-        'fecha_firma_dt',
-    )
+    @pydantic.validator('fecha_cesion_dt')
+    def validate_fecha_cesion_dt(cls, v: object) -> object:
+        if isinstance(v, datetime):
+            validate_cesion_fecha(v, cls.DATETIME_FIELDS_TZ)
+        return v
+
+    @pydantic.validator('fecha_firma_dt')
     def validate_datetime_tz(cls, v: object) -> object:
         if isinstance(v, datetime):
             tz_utils.validate_dt_tz(v, cls.DATETIME_FIELDS_TZ)
diff --git a/cl_sii/rtc/data_models_aec.py b/cl_sii/rtc/data_models_aec.py
index 99ee7475..c2c3ec4e 100644
--- a/cl_sii/rtc/data_models_aec.py
+++ b/cl_sii/rtc/data_models_aec.py
@@ -324,9 +324,9 @@ def validate_contribuyente_razon_social(cls, v: object) -> object:
         return v
 
     @pydantic.validator('fecha_cesion_dt')
-    def validate_datetime_tz(cls, v: object) -> object:
+    def validate_fecha_cesion_dt(cls, v: object) -> object:
         if isinstance(v, datetime):
-            tz_utils.validate_dt_tz(v, cls.DATETIME_FIELDS_TZ)
+            data_models.validate_cesion_fecha(v, cls.DATETIME_FIELDS_TZ)
         return v
 
     @pydantic.root_validator(skip_on_failure=True)
diff --git a/tests/test_rtc_data_models.py b/tests/test_rtc_data_models.py
index f5e36807..774653c8 100644
--- a/tests/test_rtc_data_models.py
+++ b/tests/test_rtc_data_models.py
@@ -2,7 +2,7 @@
 
 import dataclasses
 import unittest
-from datetime import date, datetime
+from datetime import date, datetime, timedelta
 
 import pydantic
 
@@ -223,7 +223,7 @@ def test_validate_dte_tipo_dte(self) -> None:
         validation_errors = assert_raises_cm.exception.errors()
         self.assertIn(expected_validation_error, validation_errors)
 
-    def test_validate_datetime_tz(self) -> None:
+    def test_validate_fecha_cesion_dt(self) -> None:
         self._set_obj_1()
 
         obj = self.obj_1
@@ -269,6 +269,33 @@ def test_validate_datetime_tz(self) -> None:
         validation_errors = assert_raises_cm.exception.errors()
         self.assertIn(expected_validation_error, validation_errors)
 
+        # Test value constraints:
+
+        tomorrow_tz_aware = tz_utils.get_now_tz_aware().astimezone(
+            CesionAltNaturalKey.DATETIME_FIELDS_TZ
+        ).replace(microsecond=0) + timedelta(days=1)
+
+        expected_validation_error = {
+            'loc': ('fecha_cesion_dt',),
+            'msg':
+                '('
+                '''\'Value of "fecha_cesion_dt" must be before or equal to the current day.\','''
+                ' datetime.datetime('
+                f'{tomorrow_tz_aware.strftime("%Y, %-m, %-d, %-H, %-M, %-S")},'
+                ' tzinfo=<DstTzInfo \'America/Santiago\' -03-1 day, 21:00:00 DST>)'
+                ')',
+            'type': 'value_error',
+        }
+
+        with self.assertRaises(pydantic.ValidationError) as assert_raises_cm:
+            dataclasses.replace(
+                obj,
+                fecha_cesion_dt=tomorrow_tz_aware,
+            )
+
+        validation_errors = assert_raises_cm.exception.errors()
+        self.assertIn(expected_validation_error, validation_errors)
+
     def test_truncate_fecha_cesion_dt_to_minutes(self) -> None:
         self._set_obj_1()