diff --git a/git_time_tracker/__init__.py b/git_time_tracker/__init__.py
index e6243f3..9e2c5ae 100644
--- a/git_time_tracker/__init__.py
+++ b/git_time_tracker/__init__.py
@@ -33,7 +33,7 @@ from collections.abc import Iterator
 from pathlib import Path
 
 from .data import HIDDEN_LABEL_PREFIX, HIDDEN_LABEL_TOTAL, WorkSample, RealizedWorkSample
-from .format import cli
+from .format import cli, icalendar
 from .source import git_repo
 
 logger = logging.getLogger(__name__)
@@ -47,7 +47,7 @@ MINUTE = datetime.timedelta(minutes=1)
 
 def filter_samples(samples: list[WorkSample], sample_filter: set[str]) -> list[WorkSample]:
     assert len(sample_filter) > 0
-    return [s for s in samples if not set(s.labels).intersection(sample_filter)]
+    return [s for s in samples if set(s.labels).intersection(sample_filter)]
 
 def heuristically_realize_samples(samples: list[WorkSample]) -> Iterator[RealizedWorkSample]:
     """Secret sauce.
@@ -92,6 +92,14 @@ def parse_arguments():
         dest='sample_filter',
         default=[],
     )
+    parser.add_argument(
+        '--format',
+        action='store',
+        type=str,
+        dest='format_mode',
+        default='cli_report',
+        choices=['cli_report', 'icalendar'],
+    )
     return parser.parse_args()
 
 
@@ -117,7 +125,10 @@ def main():
         logger.warning('Filtered down to %s samples', len(shared_time_stamps))
 
     logger.warning('Realizing %s samples', len(shared_time_stamps))
-    shared_time_stamps = heuristically_realize_samples(shared_time_stamps)
+    shared_time_stamps = list(heuristically_realize_samples(shared_time_stamps))
 
-    for t in cli.generate_report(shared_time_stamps):
-        sys.stdout.write(t)
+    if args.format_mode == 'cli_report':
+        for t in cli.generate_report(shared_time_stamps):
+            sys.stdout.write(t)
+    elif args.format_mode == 'icalendar':
+        icalendar.generate_icalendar_file(shared_time_stamps, file='./output/samples.ics')
diff --git a/git_time_tracker/format/icalendar.py b/git_time_tracker/format/icalendar.py
new file mode 100644
index 0000000..27f7360
--- /dev/null
+++ b/git_time_tracker/format/icalendar.py
@@ -0,0 +1,55 @@
+import datetime
+from collections.abc import Iterator
+import argparse
+import datetime
+import urllib.parse
+
+import icalendar
+
+from personal_data.util import load_csv_file
+
+
+from ..data import HIDDEN_LABEL_PREFIX, HIDDEN_LABEL_TOTAL, RealizedWorkSample
+
+ZERO_DURATION = datetime.timedelta(seconds=0)
+HOUR = datetime.timedelta(hours=1)
+MINUTE = datetime.timedelta(minutes=1)
+
+def generate_calendar(
+    samples: list[RealizedWorkSample],
+        ) -> icalendar.Calendar:
+    max_title_parts = 2
+
+    cal = icalendar.Calendar()
+    cal.add('prodid', '-//personal_data_calendar//example.org//')
+    cal.add('version', '2.0')
+
+    for sample in samples:
+
+        title = ' '.join(sample.labels)
+
+        description = ''
+
+        # Create event
+        event = icalendar.Event()
+
+        event.add('summary', title)
+        event.add('description', description)
+        event.add('dtstart', sample.start_at)
+        event.add('dtend', sample.end_at)
+
+        cal.add_component(event)
+        del event
+
+    return cal
+
+
+def generate_icalendar_file(
+    samples: list[RealizedWorkSample],
+    file: str,
+) -> None:
+
+    calendar = generate_calendar(samples)
+
+    with open(file, 'wb') as f:
+        f.write(calendar.to_ical())