diff --git a/ext/on-modify.timewarrior b/ext/on-modify.timewarrior
index 403fea80..6ca0b08d 100644
--- a/ext/on-modify.timewarrior
+++ b/ext/on-modify.timewarrior
@@ -42,6 +42,18 @@ old = json.loads(sys.stdin.readline())
 new = json.loads(sys.stdin.readline())
 print(json.dumps(new))
 
+def get_timew_name_from_json(json_obj):
+    # Extract attributes for use as tags.
+    tags = [json_obj['description']]
+
+    if 'project' in json_obj:
+        tags.append(json_obj['project'])
+
+    if 'tags' in json_obj:
+        tags.extend(json_obj['tags'])
+
+    return ' '.join(['"%s"' % tag for tag in tags]).encode('utf-8').strip()
+
 start_or_stop = ''
 
 # Started task.
@@ -53,16 +65,19 @@ elif 'start' not in new and 'start' in old:
     start_or_stop = 'stop'
 
 if start_or_stop:
-    # Extract attributes for use as tags.
-    tags = [new['description']]
-
-    if 'project' in new:
-        tags.append(new['project'])
-
-    if 'tags' in new:
-        tags.extend(new['tags'])
-
-    combined = ' '.join(['"%s"' % tag for tag in tags]).encode('utf-8').strip()
+    combined = get_timew_name_from_json(new)
 
     command = 'timew {0} {1} :yes'.format(start_or_stop, combined)
     subprocess.call(shlex.split(command))
+
+# Modifications to task other than start/stop
+elif 'start' in new and 'start' in old:
+    old_combined = get_timew_name_from_json(old)
+    new_combined = get_timew_name_from_json(new)
+
+    if old_combined != new_combined:
+        command = 'timew stop {0} :yes'.format(old_combined)
+        subprocess.call(shlex.split(command))
+
+        command = 'timew start {0} :yes'.format(new_combined)
+        subprocess.call(shlex.split(command))
diff --git a/test/test_on-modify.timewarrior.t.py b/test/test_on-modify.timewarrior.t.py
index 273b41d0..93e5d630 100755
--- a/test/test_on-modify.timewarrior.t.py
+++ b/test/test_on-modify.timewarrior.t.py
@@ -110,14 +110,90 @@ class TestOnModifyHookScript(TestCase):
         self.assertEqual('{"status": "pending", "entry": "20180316T231125Z", "uuid": "e11d7d19-20a7-47bb-999e-6554a70ea094", "description": "FooBar", "modified": "20180316T231055Z"}\n', out)
         self.assertEqual('', err)
 
-    def test_hook_should_process_modify(self):
-        """on-modify hook should process 'task modify'"""
+    def test_hook_should_process_modify_desc(self):
+        """on-modify hook should process 'task modify' for changing description"""
+
+        self.t("start dummy")
         out, err = self.process.communicate(input="""\
 {"description":"dummy","entry":"20180317T092629Z","modified":"20180317T092629Z","start":"20180317T092629Z","status":"pending","uuid":"3422d76c-c087-4ecd-9c62-1246b078e534"}
 {"description":"foo","entry":"20180317T092629Z","modified":"20180317T092629Z","start":"20180317T092629Z","status":"pending","uuid":"3422d76c-c087-4ecd-9c62-1246b078e534"}
 """)
 
-        self.assertEqual('{"status": "pending", "uuid": "3422d76c-c087-4ecd-9c62-1246b078e534", "modified": "20180317T092629Z", "start": "20180317T092629Z", "entry": "20180317T092629Z", "description": "foo"}\n', out)
+        self.assertRegexpMatches(out, """\
+Tracking foo
+  Started \d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}
+  Current               (\d{2}:|   )\d{2}
+  Total                ?\d{1,2}:\d{2}:\d{2}
+\{"status": "pending", "uuid": "3422d76c-c087-4ecd-9c62-1246b078e534", "modified": "20180317T092629Z", "start": "20180317T092629Z", "entry": "20180317T092629Z", "description": "foo"\}
+""")
+        self.assertEqual('', err)
+
+    def test_hook_should_process_modify_tags(self):
+        """on-modify hook should process 'task modify' for changing tags"""
+
+        self.t("start dummy tag1 tag2")
+        out, err = self.process.communicate(input="""\
+{"description":"dummy","entry":"20180317T092629Z","modified":"20180317T092629Z","start":"20180317T092629Z","status":"pending","uuid":"3422d76c-c087-4ecd-9c62-1246b078e534","tags":["tag1","tag2"]}
+{"description":"dummy","entry":"20180317T092629Z","modified":"20180317T092629Z","start":"20180317T092629Z","status":"pending","uuid":"3422d76c-c087-4ecd-9c62-1246b078e534","tags":["tag3","tag4"]}
+""")
+
+        self.assertRegexpMatches(out, """\
+Recorded dummy tag1 tag2
+  Started \d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}
+  Ended                 (\d{2}:|   )\d{2}
+  Total               ?\d{1,2}:\d{2}:\d{2}
+Tracking dummy tag3 tag4
+  Started \d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}
+  Current               (\d{2}:|   )\d{2}
+  Total                ?\d{1,2}:\d{2}:\d{2}
+\{"status": "pending", "uuid": "3422d76c-c087-4ecd-9c62-1246b078e534", "tags": \["tag3", "tag4"\], "modified": "20180317T092629Z", "start": "20180317T092629Z", "entry": "20180317T092629Z", "description": "dummy"\}
+""")
+        self.assertEqual('', err)
+
+    def test_hook_should_process_modify_project(self):
+        """on-modify hook should process 'task modify' for changing project"""
+
+        self.t("start dummy proj1")
+        out, err = self.process.communicate(input="""\
+{"description":"dummy","entry":"20180317T092629Z","modified":"20180317T092629Z","start":"20180317T092629Z","status":"pending","uuid":"3422d76c-c087-4ecd-9c62-1246b078e534","project":"proj1"}
+{"description":"dummy","entry":"20180317T092629Z","modified":"20180317T092629Z","start":"20180317T092629Z","status":"pending","uuid":"3422d76c-c087-4ecd-9c62-1246b078e534","project":"proj2"}
+""")
+
+        self.assertRegexpMatches(out, """\
+Recorded dummy proj1
+  Started \d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}
+  Ended                 (\d{2}:|   )\d{2}
+  Total               ?\d{1,2}:\d{2}:\d{2}
+Tracking dummy proj2
+  Started \d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}
+  Current               (\d{2}:|   )\d{2}
+  Total                ?\d{1,2}:\d{2}:\d{2}
+\{"status": "pending", "uuid": "3422d76c-c087-4ecd-9c62-1246b078e534", "modified": "20180317T092629Z", "project": "proj2", "start": "20180317T092629Z", "entry": "20180317T092629Z", "description": "dummy"\}
+""")
+        self.assertEqual('', err)
+
+    def test_hook_should_process_modify_not_tracked(self):
+        """on-modify hook should process 'task modify' for tasks which are not time-tracked"""
+        out, err = self.process.communicate(input="""\
+{"description":"dummy","entry":"20180317T092629Z","modified":"20180317T092629Z","status":"pending","uuid":"3422d76c-c087-4ecd-9c62-1246b078e534","project":"proj1"}
+{"description":"dummy","entry":"20180317T092629Z","modified":"20180317T092629Z","status":"pending","uuid":"3422d76c-c087-4ecd-9c62-1246b078e534","project":"proj2"}
+""")
+
+        self.assertEqual('{"status": "pending", "uuid": "3422d76c-c087-4ecd-9c62-1246b078e534", "modified": "20180317T092629Z", "project": "proj2", "entry": "20180317T092629Z", "description": "dummy"}\n', out)
+        self.assertEqual('', err)
+
+    # This is needed to test the case for task which are time-tracked and modify is called for changes other than project/tag/description
+    def test_hook_should_process_modify_due_date(self):
+        """on-modify hook should process 'task modify' for time-tracked task for changing annotations"""
+
+        self.t("start dummy")
+        out, err = self.process.communicate(input="""\
+{"status": "pending", "description": "dummy", "modified": "20180513T073915Z", "due": "20180514T000000Z", "start": "20180513T073915Z", "entry": "20180513T054634Z", "uuid": "09e9620e-8906-47ad-92c5-305894534aac"}
+{"status": "pending", "description": "dummy", "modified": "20180513T073915Z", "due": "20180512T000000Z", "start": "20180513T073915Z", "entry": "20180513T054634Z", "uuid": "09e9620e-8906-47ad-92c5-305894534aac"}
+""")
+
+        self.assertEqual('{"status": "pending", "description": "dummy", "due": "20180512T000000Z", "modified": "20180513T073915Z", "start": "20180513T073915Z", "entry": "20180513T054634Z", "uuid": "09e9620e-8906-47ad-92c5-305894534aac"}\n', out)
+
         self.assertEqual('', err)
 
     def test_hook_should_process_prepend(self):