diff --git a/cl_sii/libs/tz_utils.py b/cl_sii/libs/tz_utils.py
index 8c6ec286..9d420f07 100644
--- a/cl_sii/libs/tz_utils.py
+++ b/cl_sii/libs/tz_utils.py
@@ -1,3 +1,15 @@
+"""
+Timezone utils
+==============
+
+
+Naive and aware
+---------------
+
+These concept are defined in Python standard library module datetime
+`docs <https://docs.python.org/3/library/datetime.html#module-datetime>`_.
+
+"""
 from datetime import datetime
 from typing import Union
 
@@ -14,8 +26,12 @@
 ]
 
 
-UTC = pytz.UTC  # type: PytzTimezone
-TIMEZONE_CL_SANTIAGO = pytz.timezone('America/Santiago')  # type: PytzTimezone
+TZ_UTC = pytz.UTC  # type: PytzTimezone
+TZ_CL_SANTIAGO = pytz.timezone('America/Santiago')  # type: PytzTimezone
+
+# TODO: remove
+UTC = TZ_UTC
+TIMEZONE_CL_SANTIAGO = TZ_CL_SANTIAGO
 
 
 def get_now_tz_aware() -> datetime:
@@ -31,7 +47,7 @@ def get_now_tz_aware() -> datetime:
     #   - `pytz.UTC.localize(datetime.utcnow())`
 
     # source: 'django.utils.timezone.now' @ Django 2.1.3
-    return datetime.utcnow().replace(tzinfo=UTC)
+    return datetime.utcnow().replace(tzinfo=TZ_UTC)
 
 
 def convert_naive_dt_to_tz_aware(dt: datetime, tz: PytzTimezone) -> datetime:
@@ -44,13 +60,13 @@ def convert_naive_dt_to_tz_aware(dt: datetime, tz: PytzTimezone) -> datetime:
     >>> dt_naive.isoformat()
     '2018-10-23T01:54:13'
 
-    >>> dt_tz_aware_1 = convert_naive_dt_to_tz_aware(dt_naive, UTC)
+    >>> dt_tz_aware_1 = convert_naive_dt_to_tz_aware(dt_naive, TZ_UTC)
     >>> dt_tz_aware_1
     datetime.datetime(2018, 10, 23, 1, 54, 13, tzinfo=<UTC>)
     >>> dt_tz_aware_1.isoformat()
     '2018-10-23T04:54:13+00:00'
 
-    >>> dt_tz_aware_2 = convert_naive_dt_to_tz_aware(dt_naive, TIMEZONE_CL_SANTIAGO)
+    >>> dt_tz_aware_2 = convert_naive_dt_to_tz_aware(dt_naive, TZ_CL_SANTIAGO)
     >>> dt_tz_aware_2
     datetime.datetime(2018, 10, 23, 1, 54, 13, tzinfo=<DstTzInfo 'America/Santiago'
     -03-1 day, 21:00:00 DST>)
@@ -64,3 +80,41 @@ def convert_naive_dt_to_tz_aware(dt: datetime, tz: PytzTimezone) -> datetime:
     """
     dt_tz_aware = tz.localize(dt)  # type: datetime
     return dt_tz_aware
+
+
+def dt_is_aware(value: datetime) -> bool:
+    """
+    Return whether datetime ``value`` is "aware".
+
+    >>> dt_naive = datetime(2018, 10, 23, 1, 54, 13)
+    >>> dt_is_aware(dt_naive)
+    False
+    >>> dt_is_aware(convert_naive_dt_to_tz_aware(dt_naive, TZ_UTC))
+    True
+    >>> dt_is_aware(convert_naive_dt_to_tz_aware(dt_naive, TZ_CL_SANTIAGO))
+    True
+
+    """
+    if not isinstance(value, datetime):
+        raise TypeError
+    # source: 'django.utils.timezone.is_aware' @ Django 2.1.7
+    return value.utcoffset() is not None
+
+
+def dt_is_naive(value: datetime) -> bool:
+    """
+    Return whether datetime ``value`` is "naive".
+
+    >>> dt_naive = datetime(2018, 10, 23, 1, 54, 13)
+    >>> dt_is_naive(dt_naive)
+    True
+    >>> dt_is_naive(convert_naive_dt_to_tz_aware(dt_naive, TZ_UTC))
+    False
+    >>> dt_is_naive(convert_naive_dt_to_tz_aware(dt_naive, TZ_CL_SANTIAGO))
+    False
+
+    """
+    if not isinstance(value, datetime):
+        raise TypeError
+    # source: 'django.utils.timezone.is_naive' @ Django 2.1.7
+    return value.utcoffset() is None
diff --git a/cl_sii/rcv/parse.py b/cl_sii/rcv/parse.py
index 0e5547d9..8f22786a 100644
--- a/cl_sii/rcv/parse.py
+++ b/cl_sii/rcv/parse.py
@@ -76,7 +76,7 @@ class _RcvCsvDialect(csv.Dialect):
 class RcvCsvRowSchema(marshmallow.Schema):
 
     EXPECTED_INPUT_FIELDS = tuple(_RCV_CSV_EXPECTED_FIELD_NAMES) + (_CSV_ROW_DICT_EXTRA_FIELDS_KEY, )  # type: ignore  # noqa: E501
-    FIELD_FECHA_RECEPCION_DATETIME_TZ = tz_utils.TIMEZONE_CL_SANTIAGO
+    FIELD_FECHA_RECEPCION_DATETIME_TZ = tz_utils.TZ_CL_SANTIAGO
 
     class Meta:
         strict = True
diff --git a/tests/test_libs_tz_utils.py b/tests/test_libs_tz_utils.py
index 8d2bcb32..4fe2145b 100644
--- a/tests/test_libs_tz_utils.py
+++ b/tests/test_libs_tz_utils.py
@@ -1,16 +1,29 @@
 import unittest
 
-from cl_sii.libs.tz_utils import convert_naive_dt_to_tz_aware, get_now_tz_aware  # noqa: F401
+from cl_sii.libs.tz_utils import (  # noqa: F401
+    convert_naive_dt_to_tz_aware, dt_is_aware, dt_is_naive, get_now_tz_aware,
+    PytzTimezone, TZ_CL_SANTIAGO, TZ_UTC,
+)
 
 
 class FunctionsTest(unittest.TestCase):
 
     def test_get_now_tz_aware(self) -> None:
-        # TODO: implement!
+        # TODO: implement for 'get_now_tz_aware'
         # Reuse doctests/examples in function docstring.
         pass
 
     def test_convert_naive_dt_to_tz_aware(self) -> None:
-        # TODO: implement!
+        # TODO: implement for 'convert_naive_dt_to_tz_aware'
+        # Reuse doctests/examples in function docstring.
+        pass
+
+    def test_dt_is_aware(self) -> None:
+        # TODO: implement for 'dt_is_aware'
+        # Reuse doctests/examples in function docstring.
+        pass
+
+    def test_dt_is_naive(self) -> None:
+        # TODO: implement for 'dt_is_naive'
         # Reuse doctests/examples in function docstring.
         pass