diff --git a/lib/model/alarm.dart b/lib/model/alarm.dart
index 67a7a37..7a6e8f9 100644
--- a/lib/model/alarm.dart
+++ b/lib/model/alarm.dart
@@ -1,18 +1,23 @@
+import 'fixed_time_alarm.dart';
 import 'location_alarm.dart';
-import 'time_alarm.dart';
+import 'relative_time_alarm.dart';
 
 abstract class Alarm {
   String get id;
   String get taskId;
+  AlarmType get alarmType;
   Map<String, dynamic> toJson();
 
   factory Alarm.fromJson(Map<String, dynamic> json) {
-    if (json.containsKey('triggerAt')) {
-      return TimeAlarm.fromJson(json);
-    }
-
-    if (json.containsKey('location')) {
-      return LocationAlarm.fromJson(json);
+    if (json.containsKey('alarmType')) {
+      switch (json['alarmType'] as String) {
+        case 'timeFixed':
+          return FixedTimeAlarm.fromJson(json);
+        case 'timeRelative':
+          return RelativeTimeAlarm.fromJson(json);
+        case 'location':
+          return LocationAlarm.fromJson(json);
+      }
     }
 
     throw ArgumentError('Unknown alarm type');
diff --git a/lib/model/callback_models/create_fixed_time_alarm_request.dart b/lib/model/callback_models/create_fixed_time_alarm_request.dart
new file mode 100644
index 0000000..7bdeb06
--- /dev/null
+++ b/lib/model/callback_models/create_fixed_time_alarm_request.dart
@@ -0,0 +1,9 @@
+import '../alarm.dart';
+import 'create_alarm_request.dart';
+
+class CreateFixedTimeAlarmRequest extends CreateAlarmRequest {
+  final DateTime? triggerAt;
+
+  CreateFixedTimeAlarmRequest({this.triggerAt})
+    : super(alarmType: AlarmType.timeFixed);
+}
diff --git a/lib/model/callback_models/create_relative_time_alarm_request.dart b/lib/model/callback_models/create_relative_time_alarm_request.dart
new file mode 100644
index 0000000..93ea8fb
--- /dev/null
+++ b/lib/model/callback_models/create_relative_time_alarm_request.dart
@@ -0,0 +1,9 @@
+import '../alarm.dart' show AlarmType;
+import 'create_alarm_request.dart';
+
+class CreateRelativeTimeAlarmRequest extends CreateAlarmRequest {
+  final DateTime? triggerAt;
+
+  CreateRelativeTimeAlarmRequest({this.triggerAt})
+    : super(alarmType: AlarmType.timeRelative);
+}
diff --git a/lib/model/callback_models/create_time_alarm_request.dart b/lib/model/callback_models/create_time_alarm_request.dart
deleted file mode 100644
index 27f5b49..0000000
--- a/lib/model/callback_models/create_time_alarm_request.dart
+++ /dev/null
@@ -1,7 +0,0 @@
-import 'create_alarm_request.dart';
-
-class CreateTimeAlarmRequest extends CreateAlarmRequest {
-  final DateTime? triggerAt;
-
-  CreateTimeAlarmRequest({this.triggerAt, required super.alarmType});
-}
diff --git a/lib/model/time_alarm.dart b/lib/model/fixed_time_alarm.dart
similarity index 65%
rename from lib/model/time_alarm.dart
rename to lib/model/fixed_time_alarm.dart
index f7aabc5..ba7d0d9 100644
--- a/lib/model/time_alarm.dart
+++ b/lib/model/fixed_time_alarm.dart
@@ -1,6 +1,6 @@
 import 'alarm.dart';
 
-class TimeAlarm implements Alarm {
+class FixedTimeAlarm implements Alarm {
   @override
   final String id;
 
@@ -9,14 +9,17 @@ class TimeAlarm implements Alarm {
 
   final DateTime triggerAt;
 
-  const TimeAlarm({
+  @override
+  final AlarmType alarmType;
+
+  const FixedTimeAlarm({
     required this.id,
     required this.taskId,
     required this.triggerAt,
-  });
+  }) : alarmType = AlarmType.timeFixed;
 
-  factory TimeAlarm.fromJson(Map<String, dynamic> json) {
-    return TimeAlarm(
+  factory FixedTimeAlarm.fromJson(Map<String, dynamic> json) {
+    return FixedTimeAlarm(
       id: json['id'] as String,
       taskId: json['taskId'] as String,
       triggerAt: DateTime.parse(json['triggerAt'] as String),
@@ -29,6 +32,7 @@ class TimeAlarm implements Alarm {
       'id': id,
       'taskId': taskId,
       'triggerAt': triggerAt.toIso8601String(),
+      'alarmType': alarmType,
     };
   }
 }
diff --git a/lib/model/location_alarm.dart b/lib/model/location_alarm.dart
index 0d8d10a..695c6e7 100644
--- a/lib/model/location_alarm.dart
+++ b/lib/model/location_alarm.dart
@@ -12,12 +12,15 @@ class LocationAlarm implements Alarm {
 
   final int radiusMeters;
 
+  @override
+  final AlarmType alarmType;
+
   const LocationAlarm({
     required this.id,
     required this.taskId,
     required this.location,
     required this.radiusMeters,
-  });
+  }) : alarmType = AlarmType.location;
 
   factory LocationAlarm.fromJson(Map<String, dynamic> json) {
     return LocationAlarm(
@@ -35,6 +38,7 @@ class LocationAlarm implements Alarm {
       'taskId': taskId,
       'location': location.toJson(),
       'radiusMeters': radiusMeters,
+      'alarmType': alarmType,
     };
   }
 }
diff --git a/lib/model/relative_time_alarm.dart b/lib/model/relative_time_alarm.dart
new file mode 100644
index 0000000..709aa97
--- /dev/null
+++ b/lib/model/relative_time_alarm.dart
@@ -0,0 +1,38 @@
+import 'alarm.dart';
+
+class RelativeTimeAlarm implements Alarm {
+  @override
+  final String id;
+
+  @override
+  final String taskId;
+
+  final DateTime triggerAt;
+
+  @override
+  final AlarmType alarmType;
+
+  const RelativeTimeAlarm({
+    required this.id,
+    required this.taskId,
+    required this.triggerAt,
+  }) : alarmType = AlarmType.timeRelative;
+
+  factory RelativeTimeAlarm.fromJson(Map<String, dynamic> json) {
+    return RelativeTimeAlarm(
+      id: json['id'] as String,
+      taskId: json['taskId'] as String,
+      triggerAt: DateTime.parse(json['triggerAt'] as String),
+    );
+  }
+
+  @override
+  Map<String, dynamic> toJson() {
+    return {
+      'id': id,
+      'taskId': taskId,
+      'triggerAt': triggerAt.toIso8601String(),
+      'alarmType': alarmType,
+    };
+  }
+}