diff --git a/constants.py b/constants.py
index a230481..bac9422 100644
--- a/constants.py
+++ b/constants.py
@@ -4,3 +4,8 @@ BREAK_START_ENTRY_CODE_ID = 48
 BREAK_END_ENTRY_CODE_ID = 64
 
 PUNCH_COMMANDS = ("punch_in", "punch_out", "break_start", "break_end")
+
+SIMPLE_DATETIME_FORMAT = "%d.%m.%Y_%H:%M"
+SIMPLE_DATETIME_FORMAT_HUMAN = "DD.MM.YYYY_hh:mm"
+SIMPLE_DATE_FORMAT = "%d.%m.%Y"
+SIMPLE_TIME_FORMAT = "%H:%M"
diff --git a/timebot.py b/timebot.py
index 794a83f..61c1ede 100644
--- a/timebot.py
+++ b/timebot.py
@@ -8,7 +8,8 @@ import sys
 import requests as requests
 
 from constants import COMING_ENTRY_CODE_ID, LEAVING_ENTRY_CODE_ID, PUNCH_COMMANDS, BREAK_START_ENTRY_CODE_ID, \
-    BREAK_END_ENTRY_CODE_ID
+    BREAK_END_ENTRY_CODE_ID, SIMPLE_DATE_FORMAT, SIMPLE_TIME_FORMAT, SIMPLE_DATETIME_FORMAT, \
+    SIMPLE_DATETIME_FORMAT_HUMAN
 
 logger = logging.getLogger()
 logging.basicConfig(level=logging.INFO)
@@ -59,16 +60,17 @@ class TimeBot:
         request = session.post(self.baseurl + "Account/LogOn", data=login_data)
         request.raise_for_status()
 
-    def add_entry(self, punch_date: str, punch_time: str, entry_code: int, note: str = None) -> requests.Response:
+    def add_entry(self, punch_datetime: datetime.datetime, entry_code: int, note: str = None) -> requests.Response:
         """
         Add mobatime entry.
 
-        :param str punch_date: date string in format: ``DD.MM.YYYY``
-        :param str punch_time: time string in format: ``hh:mm``
+        :param datetime.datetime punch_datetime: datetim object
         :param int entry_code: entry type code
         :param str note: free text note added to the Mobatime entry
         :return: requests response object
         """
+        punch_date = punch_datetime.strftime(SIMPLE_DATE_FORMAT)
+        punch_time = punch_datetime.strftime(SIMPLE_TIME_FORMAT)
         entry_data = {
             "periode0Date": punch_date,
             "periode0Time": punch_time,
@@ -154,37 +156,33 @@ class TimeBot:
         request.raise_for_status()
         return request.json()["data"]
 
-    def punch_in(self, punch_in_date: str, punch_in_time: str):
+    def punch_in(self, punch_datetime: datetime.datetime):
         """
-        :param str punch_in_date: date string in format: ``DD.MM.YYYY``
-        :param str punch_in_time: time string in format: ``hh:mm``
+        :param datetime.datetime punch_datetime: datetime object
         :raises: on status code != 2xx
         """
-        self.add_entry(punch_in_date, punch_in_time, COMING_ENTRY_CODE_ID, note="da").raise_for_status()
+        self.add_entry(punch_datetime, COMING_ENTRY_CODE_ID, note="da").raise_for_status()
 
-    def punch_out(self, punch_out_date: str, punch_out_time: str):
+    def punch_out(self, punch_datetime: datetime.datetime):
         """
-        :param str punch_out_date: date string in format: ``DD.MM.YYYY``
-        :param str punch_out_time: time string in format: ``hh:mm``
+        :param datetime.datetime punch_datetime: datetime object
         :raises: on status code != 2xx
         """
-        self.add_entry(punch_out_date, punch_out_time, LEAVING_ENTRY_CODE_ID, note="weg").raise_for_status()
+        self.add_entry(punch_datetime, LEAVING_ENTRY_CODE_ID, note="weg").raise_for_status()
 
-    def break_start(self, punch_date: str, punch_time: str):
+    def break_start(self, punch_datetime: datetime.datetime):
         """
-        :param str punch_date: date string in format: ``DD.MM.YYYY``
-        :param str punch_time: time string in format: ``hh:mm``
+        :param datetime.datetime punch_datetime: datetime object
         :raises: on status code != 2xx
         """
-        self.add_entry(punch_date, punch_time, BREAK_START_ENTRY_CODE_ID, note="pause").raise_for_status()
+        self.add_entry(punch_datetime, BREAK_START_ENTRY_CODE_ID, note="pause").raise_for_status()
 
-    def break_end(self, punch_date: str, punch_time: str):
+    def break_end(self, punch_datetime: datetime.datetime):
         """
-        :param str punch_date: date string in format: ``DD.MM.YYYY``
-        :param str punch_time: time string in format: ``hh:mm``
+        :param datetime.datetime punch_datetime: datetime object
         :raises: on status code != 2xx
         """
-        self.add_entry(punch_date, punch_time, BREAK_END_ENTRY_CODE_ID, note="pause ende").raise_for_status()
+        self.add_entry(punch_datetime, BREAK_END_ENTRY_CODE_ID, note="pause ende").raise_for_status()
 
 
 if __name__ == '__main__':
@@ -202,14 +200,16 @@ if __name__ == '__main__':
                               help="type of time entry; this can be `punch_in`, `punch_out`, `break_start`, `break_end`",
                               default="punch_in",
                               choices=PUNCH_COMMANDS)
-    parser_punch.add_argument("-s", help="timestamp in format `DD.MM.YYYY_hh:mm` or `now`", default="now")
+    parser_punch.add_argument("-s", help=f"timestamp in format `{SIMPLE_DATETIME_FORMAT_HUMAN}` or `now`", default="now")
 
     # subparser command: `list-entries`
     parser_list_entries = subparsers.add_parser("list-entries", help="use this command to list your time entries")
     parser_list_entries.add_argument("--start-date",
-                                     help="start date filter in format `DD.MM.YYYY_hh:mm` (default: now - 10days; unset for default)")
+                                     help=f"start date filter in format `{SIMPLE_DATETIME_FORMAT_HUMAN}` "
+                                          f"(default: now - 10days; unset for default)")
     parser_list_entries.add_argument("--end-date",
-                                     help="end date filter in format `DD.MM.YYYY_hh:mm` (default: now; unset for default)")
+                                     help=f"end date filter in format `{SIMPLE_DATETIME_FORMAT_HUMAN}` "
+                                          f"(default: now; unset for default)")
     parser_list_entries.add_argument("--items", help="max items to request per page", default=20, type=int)
 
     args = parser.parse_args()
@@ -227,21 +227,24 @@ if __name__ == '__main__':
     tb = TimeBot(baseurl=config["general"]["baseurl"], user=args.u, password=password)
     if args.subparser_name == "punch":
         if args.s == "now":
-            now = datetime.datetime.now()
-            punch_date = now.strftime("%d.%m.%Y")
-            punch_time = now.strftime("%H:%M")
+            punch_datetime = datetime.datetime.now()
         else:
-            punch_date = args.s.split("_")[0]
-            punch_time = args.s.split("_")[1]
-        logger.info("running `{}` with date `{}` and time `{}`".format(args.t, punch_date, punch_time))
-        getattr(tb, args.t)(punch_date, punch_time)
+            punch_datetime = datetime.datetime.strptime(args.s, SIMPLE_DATETIME_FORMAT)
+        logger.info("running `{}` with date `{}` and time `{}`".format(
+            args.t,
+            punch_datetime.strftime(SIMPLE_DATE_FORMAT),
+            punch_datetime.strftime(SIMPLE_TIME_FORMAT),
+        ))
+        getattr(tb, args.t)(punch_datetime)
+    elif args.subparser_name == "smart-punch":
+        pass
     elif args.subparser_name == "list-entries":
         end_date = None
         if args.end_date:
-            end_date = datetime.datetime.strptime(args.end_date, "%d.%m.%Y_%H:%M")
+            end_date = datetime.datetime.strptime(args.end_date, SIMPLE_DATETIME_FORMAT)
         start_date = None
         if args.start_date:
-            start_date = datetime.datetime.strptime(args.start_date, "%d.%m.%Y_%H:%M")
+            start_date = datetime.datetime.strptime(args.start_date, SIMPLE_DATETIME_FORMAT)
         data = tb.get_entries(entries=args.items, start_date=start_date, end_date=end_date)
         for i in data:
             print("Entry: {} - DateTime: {} - Note: {}".format(i["entryName"], i["dateTime"], i["note"]))