diff --git a/lib/data/models/task_model.dart b/lib/data/models/task_model.dart
index 23b1629e0..94e527402 100644
--- a/lib/data/models/task_model.dart
+++ b/lib/data/models/task_model.dart
@@ -74,9 +74,13 @@ abstract class TaskTime implements Built<TaskTime, TaskTimeBuilder> {
         endDate != null ? (endDate.millisecondsSinceEpoch / 1000).floor() : 0
       ];
 
+  TaskTime get stop => rebuild((b) => b..endDate = DateTime.now().toUtc());
+
   bool equalTo(TaskTime taskTime) =>
       startDate == taskTime.startDate && endDate == taskTime.endDate;
 
+  bool get isRunning => endDate == null;
+
   static Serializer<TaskTime> get serializer => _$taskTimeSerializer;
 }
 
@@ -94,7 +98,7 @@ abstract class TaskEntity extends Object
       timeLog: isRunning
           ? '[[${(DateTime.now().millisecondsSinceEpoch / 1000).floor()},0]]'
           : '',
-      isRunning: false,
+      isRunning: isRunning,
       customValue1: '',
       customValue2: '',
       updatedAt: 0,
@@ -132,7 +136,8 @@ abstract class TaskEntity extends Object
 
       final taskTime = TaskTime(
           startDate: convertTimestampToDate(startDate).toUtc(),
-          endDate: endDate > 0 ? convertTimestampToDate(endDate).toUtc() : null);
+          endDate:
+              endDate > 0 ? convertTimestampToDate(endDate).toUtc() : null);
 
       details.add(taskTime);
     });
@@ -140,31 +145,43 @@ abstract class TaskEntity extends Object
     return details;
   }
 
-  String addTaskTime(TaskTime time) {
+  TaskEntity addTaskTime(TaskTime time) {
     final List<dynamic> taskTimes =
-    timeLog.isNotEmpty ? jsonDecode(timeLog) : <dynamic>[];
+        timeLog.isNotEmpty ? jsonDecode(timeLog) : <dynamic>[];
 
     taskTimes.add(time.asList);
 
-    return jsonEncode(taskTimes);
+    return rebuild((b) => b
+      ..timeLog = jsonEncode(taskTimes)
+      ..isRunning = time.isRunning);
   }
 
-  String updateTaskTime(TaskTime time, int index) {
+  TaskEntity updateTaskTime(TaskTime time, int index) {
     final List<dynamic> taskTimes =
-    timeLog.isNotEmpty ? jsonDecode(timeLog) : <dynamic>[];
+        timeLog.isNotEmpty ? jsonDecode(timeLog) : <dynamic>[];
 
     taskTimes[index] = time.asList;
 
-    return jsonEncode(taskTimes);
+    final bool isRunning =
+        taskTimes.last != null && taskTimes.length > 1 && taskTimes.last > 0;
+
+    return rebuild((b) => b
+      ..timeLog = jsonEncode(taskTimes)
+      ..isRunning = isRunning);
   }
 
-  String deleteTaskTime(int index) {
+  TaskEntity deleteTaskTime(int index) {
     final List<dynamic> taskTimes =
-    timeLog.isNotEmpty ? jsonDecode(timeLog) : <dynamic>[];
+        timeLog.isNotEmpty ? jsonDecode(timeLog) : <dynamic>[];
 
     taskTimes.removeAt(index);
 
-    return jsonEncode(taskTimes);
+    final bool isRunning =
+        taskTimes.last != null && taskTimes.length > 1 && taskTimes.last > 0;
+
+    return rebuild((b) => b
+      ..timeLog = jsonEncode(taskTimes)
+      ..isRunning = isRunning);
   }
 
   double calculateAmount(double taskRate) =>
diff --git a/lib/redux/task/task_reducer.dart b/lib/redux/task/task_reducer.dart
index 44ffbdde9..7817fa18b 100644
--- a/lib/redux/task/task_reducer.dart
+++ b/lib/redux/task/task_reducer.dart
@@ -106,16 +106,15 @@ ListUIState _sortTasks(ListUIState taskListState, SortTasks action) {
 }
 
 TaskEntity _addTaskTime(TaskEntity task, AddTaskTime action) {
-  return task.rebuild((b) => b..timeLog = task.addTaskTime(action.taskTime));
+  return task.addTaskTime(action.taskTime);
 }
 
 TaskEntity _removeTaskTime(TaskEntity task, DeleteTaskTime action) {
-  return task.rebuild((b) => b..timeLog = task.deleteTaskTime(action.index));
+  return task.deleteTaskTime(action.index);
 }
 
 TaskEntity _updateTaskTime(TaskEntity task, UpdateTaskTime action) {
-  return task.rebuild(
-      (b) => b..timeLog = task.updateTaskTime(action.taskTime, action.index));
+  return task.updateTaskTime(action.taskTime, action.index);
 }
 
 final tasksReducer = combineReducers<TaskState>([
diff --git a/lib/ui/task/view/task_view.dart b/lib/ui/task/view/task_view.dart
index d0be2b38c..1645f0bfd 100644
--- a/lib/ui/task/view/task_view.dart
+++ b/lib/ui/task/view/task_view.dart
@@ -58,6 +58,7 @@ class _TaskViewState extends State<TaskView> {
     List<Widget> _buildView() {
       final widgets = <Widget>[
         TwoValueHeader(
+          backgroundColor: task.isRunning ? Colors.green : null,
           label1: localization.duration,
           value1: formatDuration(task.calculateDuration),
           label2: localization.amount,
@@ -166,10 +167,10 @@ class _TaskViewState extends State<TaskView> {
           },
         ),
         floatingActionButton: FloatingActionButton(
-          backgroundColor: Theme.of(context).primaryColorDark,
-          onPressed: () => null,
+          backgroundColor: task.isRunning ? Colors.red : Colors.green,
+          onPressed: () => viewModel.onFabPressed(),
           child: Icon(
-            Icons.add,
+            task.isRunning ? Icons.stop : Icons.play_arrow,
             color: Colors.white,
           ),
           tooltip: localization.newTask,
diff --git a/lib/ui/task/view/task_view_vm.dart b/lib/ui/task/view/task_view_vm.dart
index 00d276a27..84c597bf6 100644
--- a/lib/ui/task/view/task_view_vm.dart
+++ b/lib/ui/task/view/task_view_vm.dart
@@ -38,6 +38,7 @@ class TaskViewScreen extends StatelessWidget {
 
 class TaskViewVM {
   TaskViewVM({
+    @required this.onFabPressed,
     @required this.task,
     @required this.client,
     @required this.project,
@@ -76,6 +77,16 @@ class TaskViewVM {
         task: task,
         client: client,
         project: project,
+        onFabPressed: () {
+          if (task.isRunning) {
+            final taskTimes = task.taskTimes;
+            final taskTime = taskTimes.last.stop;
+            store.dispatch(UpdateTaskTime(
+                index: taskTimes.length - 1, taskTime: taskTime));
+          } else {
+            store.dispatch(AddTaskTime(TaskTime()));
+          }
+        },
         onClientPressed: (context, [longPress = false]) {
           if (longPress) {
             store.dispatch(EditClient(client: client, context: context));
@@ -92,18 +103,18 @@ class TaskViewVM {
           }
         },
         onEditPressed: (BuildContext context, [TaskTime taskItem]) {
-          final Completer<TaskEntity> completer =
-          new Completer<TaskEntity>();
+          final Completer<TaskEntity> completer = new Completer<TaskEntity>();
           store.dispatch(EditTask(
-              task: task,
-              taskTime: taskItem,
-              context: context,
-              completer: completer,));
+            task: task,
+            taskTime: taskItem,
+            context: context,
+            completer: completer,
+          ));
           completer.future.then((task) {
             Scaffold.of(context).showSnackBar(SnackBar(
                 content: SnackBarRow(
-                  message: AppLocalization.of(context).updatedTask,
-                )));
+              message: AppLocalization.of(context).updatedTask,
+            )));
           });
         },
         onRefreshed: (context) => _handleRefresh(context),
@@ -140,6 +151,7 @@ class TaskViewVM {
   final Function(BuildContext, EntityAction) onActionSelected;
   final Function(BuildContext, [TaskTime]) onEditPressed;
   final Function onBackPressed;
+  final Function onFabPressed;
   final Function(BuildContext) onRefreshed;
   final Function(BuildContext, [bool]) onClientPressed;
   final Function(BuildContext, [bool]) onProjectPressed;