diff --git a/backend/.idea/workspace.xml b/backend/.idea/workspace.xml
index c7a54fb..eea8ce0 100644
--- a/backend/.idea/workspace.xml
+++ b/backend/.idea/workspace.xml
@@ -7,6 +7,7 @@
     <list default="true" id="3a869f59-290a-4ab2-b036-a878ce801bc4" name="Changes" comment="Load worked minutes when reloading dashboard">
       <change beforePath="$PROJECT_DIR$/.idea/workspace.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/workspace.xml" afterDir="false" />
       <change beforePath="$PROJECT_DIR$/src/main/java/core/services/TaskScheduleService.java" beforeDir="false" afterPath="$PROJECT_DIR$/src/main/java/core/services/TaskScheduleService.java" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/../frontend/src/app/dashboard/forgotten-task-start-dialog/forgotten-task-start-dialog.component.ts" beforeDir="false" afterPath="$PROJECT_DIR$/../frontend/src/app/dashboard/forgotten-task-start-dialog/forgotten-task-start-dialog.component.ts" afterDir="false" />
     </list>
     <option name="SHOW_DIALOG" value="false" />
     <option name="HIGHLIGHT_CONFLICTS" value="true" />
@@ -16,16 +17,16 @@
   <component name="FileTemplateManagerImpl">
     <option name="RECENT_TEMPLATES">
       <list>
-        <option value="Enum" />
         <option value="Interface" />
         <option value="Class" />
+        <option value="Enum" />
       </list>
     </option>
   </component>
   <component name="Git.Settings">
     <option name="RECENT_BRANCH_BY_REPOSITORY">
       <map>
-        <entry key="$PROJECT_DIR$/.." value="issue-23" />
+        <entry key="$PROJECT_DIR$/.." value="issue-29" />
       </map>
     </option>
     <option name="RECENT_GIT_ROOT_PATH" value="$PROJECT_DIR$/.." />
@@ -259,7 +260,8 @@
     <MESSAGE value="Remove update spamming in console" />
     <MESSAGE value="Start task now from Taskoverview in Dashboard" />
     <MESSAGE value="Load worked minutes when reloading dashboard" />
-    <option name="LAST_COMMIT_MESSAGE" value="Load worked minutes when reloading dashboard" />
+    <MESSAGE value="Check if there is another active schedule when starting task now" />
+    <option name="LAST_COMMIT_MESSAGE" value="Check if there is another active schedule when starting task now" />
   </component>
   <component name="XDebuggerManager">
     <breakpoint-manager>
@@ -271,14 +273,19 @@
         </line-breakpoint>
         <line-breakpoint enabled="true" type="java-line">
           <url>file://$PROJECT_DIR$/src/main/java/core/services/TaskScheduleService.java</url>
-          <line>86</line>
+          <line>87</line>
           <option name="timeStamp" value="5" />
         </line-breakpoint>
         <line-breakpoint enabled="true" type="java-line">
           <url>file://$PROJECT_DIR$/src/main/java/core/services/TaskScheduleService.java</url>
-          <line>93</line>
+          <line>94</line>
           <option name="timeStamp" value="6" />
         </line-breakpoint>
+        <line-breakpoint enabled="true" type="java-line">
+          <url>file://$PROJECT_DIR$/src/main/java/core/services/TaskScheduleService.java</url>
+          <line>202</line>
+          <option name="timeStamp" value="10" />
+        </line-breakpoint>
       </breakpoints>
     </breakpoint-manager>
   </component>
diff --git a/backend/src/main/java/core/api/controller/ScheduleController.java b/backend/src/main/java/core/api/controller/ScheduleController.java
index cbdf1a3..7168f1a 100644
--- a/backend/src/main/java/core/api/controller/ScheduleController.java
+++ b/backend/src/main/java/core/api/controller/ScheduleController.java
@@ -201,4 +201,23 @@ public class ScheduleController {
         int workedMinutes = taskScheduleService.getWorkedMinutes(user.get());
         return ResponseEntity.ok(new ScheduleStatus(workedMinutes, taskScheduleService.isAnyScheduleMissed(user.get())));
     }
+
+    @PostMapping("/schedules/{taskID}/forgotten")
+    public ResponseEntity<?> registerForgottenActivity(@PathVariable long taskID, @Valid @RequestBody ForgottenActivity forgottenActivity) {
+        PermissionResult<Task> permissionResult = taskService.getTaskPermissions(taskID, SecurityContextHolder.getContext().getAuthentication().getName());
+        if(!permissionResult.isHasPermissions()) {
+            return ResponseEntity.status(403).body(new SimpleStatusResponse("failed"));
+        }
+
+        if(permissionResult.getExitCode() == ServiceExitCode.MISSING_ENTITY) {
+            return ResponseEntity.status(404).body(new SimpleStatusResponse("failed"));
+        }
+
+        ServiceResult<Integer> serviceResult = taskScheduleService.registerForgottenActivity(permissionResult.getResult(), forgottenActivity);
+        if(serviceResult.getExitCode() == ServiceExitCode.INVALID_OPERATION) {
+            return ResponseEntity.status(400).body(new SimpleStatusResponse("failed"));
+        } else {
+            return ResponseEntity.ok(new TaskScheduleStopResponse(serviceResult.getResult()));
+        }
+    }
 }
diff --git a/backend/src/main/java/core/api/controller/TaskController.java b/backend/src/main/java/core/api/controller/TaskController.java
index 7ec2b13..5be2520 100644
--- a/backend/src/main/java/core/api/controller/TaskController.java
+++ b/backend/src/main/java/core/api/controller/TaskController.java
@@ -4,6 +4,7 @@ import core.api.models.auth.SimpleStatusResponse;
 import core.api.models.timemanager.taskSchedule.ScheduleInfo;
 import core.api.models.timemanager.tasks.TaskEntityInfo;
 import core.api.models.timemanager.tasks.TaskFieldInfo;
+import core.api.models.timemanager.tasks.TaskShortInfo;
 import core.entities.timemanager.Task;
 import core.entities.timemanager.Taskgroup;
 import core.services.*;
@@ -13,6 +14,9 @@ import org.springframework.security.core.context.SecurityContextHolder;
 import org.springframework.web.bind.annotation.*;
 
 import javax.validation.Valid;
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
 
 @CrossOrigin(origins = "*", maxAge = 3600)
 @RestController
@@ -27,6 +31,24 @@ public class TaskController {
         this.taskgroupService = taskgroupService;
     }
 
+    @GetMapping("/tasks/all/{finished}")
+    public ResponseEntity<List<TaskShortInfo>> loadAllTasks(@PathVariable boolean finished) {
+        List<Task> taskList = taskService.loadAllTasks(SecurityContextHolder.getContext().getAuthentication().getName(), finished);
+        List<TaskShortInfo> taskShortInfos = new ArrayList<>();
+        for(Task task : taskList) {
+            List<Taskgroup> ancestors = Taskgroup.getAncestorList(task.getTaskgroup());
+            ancestors.add(task.getTaskgroup());
+            StringBuilder builder = new StringBuilder();
+            for(Taskgroup taskgroup : ancestors) {
+                builder.append(taskgroup.getTaskgroupName()).append("/");
+            }
+            builder.append(task.getTaskName());
+            taskShortInfos.add(new TaskShortInfo(task.getTaskID(), builder.toString()));
+
+        }
+        return ResponseEntity.ok(taskShortInfos);
+    }
+
     @GetMapping("/tasks/{taskgroupID}/{status}")
     public ResponseEntity<?> listTasksOfTaskgroup(@PathVariable long taskgroupID, @PathVariable String status) {
         PermissionResult<Taskgroup> taskgroupPermissionResult = taskgroupService.getTaskgroupByIDAndUsername(taskgroupID, SecurityContextHolder.getContext().getAuthentication().getName());
diff --git a/backend/src/main/java/core/api/models/timemanager/taskSchedule/ForgottenActivity.java b/backend/src/main/java/core/api/models/timemanager/taskSchedule/ForgottenActivity.java
new file mode 100644
index 0000000..d8634d1
--- /dev/null
+++ b/backend/src/main/java/core/api/models/timemanager/taskSchedule/ForgottenActivity.java
@@ -0,0 +1,22 @@
+package core.api.models.timemanager.taskSchedule;
+
+public class ForgottenActivity {
+    private ForgottenActivityMode mode;
+    private int minutesSpent;
+
+    public ForgottenActivityMode getMode() {
+        return mode;
+    }
+
+    public void setMode(ForgottenActivityMode mode) {
+        this.mode = mode;
+    }
+
+    public int getMinutesSpent() {
+        return minutesSpent;
+    }
+
+    public void setMinutesSpent(int minutesSpent) {
+        this.minutesSpent = minutesSpent;
+    }
+}
diff --git a/backend/src/main/java/core/api/models/timemanager/taskSchedule/ForgottenActivityMode.java b/backend/src/main/java/core/api/models/timemanager/taskSchedule/ForgottenActivityMode.java
new file mode 100644
index 0000000..70cd031
--- /dev/null
+++ b/backend/src/main/java/core/api/models/timemanager/taskSchedule/ForgottenActivityMode.java
@@ -0,0 +1,8 @@
+package core.api.models.timemanager.taskSchedule;
+
+public enum ForgottenActivityMode {
+
+    MANUAL,
+    LAST,
+    PLANNED
+}
diff --git a/backend/src/main/java/core/api/models/timemanager/tasks/TaskShortInfo.java b/backend/src/main/java/core/api/models/timemanager/tasks/TaskShortInfo.java
index c1e5c6b..9444fce 100644
--- a/backend/src/main/java/core/api/models/timemanager/tasks/TaskShortInfo.java
+++ b/backend/src/main/java/core/api/models/timemanager/tasks/TaskShortInfo.java
@@ -12,6 +12,11 @@ public class TaskShortInfo {
         this.taskName = task.getTaskName();
     }
 
+    public TaskShortInfo(long taskID, String taskName) {
+        this.taskID = taskID;
+        this.taskName = taskName;
+    }
+
     public long getTaskID() {
         return taskID;
     }
diff --git a/backend/src/main/java/core/entities/timemanager/Task.java b/backend/src/main/java/core/entities/timemanager/Task.java
index 92b45e7..9154f0f 100644
--- a/backend/src/main/java/core/entities/timemanager/Task.java
+++ b/backend/src/main/java/core/entities/timemanager/Task.java
@@ -146,4 +146,8 @@ public class Task {
         }
         return false;
     }
+
+    public void increaseActiveTime(int minutesSpent) {
+        this.workTime += minutesSpent;
+    }
 }
diff --git a/backend/src/main/java/core/entities/timemanager/Taskgroup.java b/backend/src/main/java/core/entities/timemanager/Taskgroup.java
index 864c9b0..be2d450 100644
--- a/backend/src/main/java/core/entities/timemanager/Taskgroup.java
+++ b/backend/src/main/java/core/entities/timemanager/Taskgroup.java
@@ -95,6 +95,7 @@ public class Taskgroup {
             ancestors.add(currentTaskgroup.parent);
             currentTaskgroup = currentTaskgroup.parent;
         }
+        //ancestors.add(taskgroup);
         return ancestors;
     }
 
diff --git a/backend/src/main/java/core/repositories/timemanager/BasicTaskScheduleRepository.java b/backend/src/main/java/core/repositories/timemanager/BasicTaskScheduleRepository.java
index 9a735dd..5a1b24a 100644
--- a/backend/src/main/java/core/repositories/timemanager/BasicTaskScheduleRepository.java
+++ b/backend/src/main/java/core/repositories/timemanager/BasicTaskScheduleRepository.java
@@ -36,4 +36,7 @@ public interface BasicTaskScheduleRepository extends CrudRepository<BasicTaskSch
     Optional<BasicTaskSchedule> findActiveTaskSchedule(String username);
 
     List<BasicTaskSchedule> findAllByStartTimeIsNull();
+
+    @Query(value = "SELECT bts FROM BasicTaskSchedule bts WHERE bts.task.taskgroup.user = ?1 AND bts.scheduleDate = ?2 AND bts.finishedTime IS NOT NULL")
+    List<BasicTaskSchedule> findAllFinishedByUserAndDate(User user, LocalDate now);
 }
diff --git a/backend/src/main/java/core/repositories/timemanager/TaskRepository.java b/backend/src/main/java/core/repositories/timemanager/TaskRepository.java
index 4659263..59f3fe4 100644
--- a/backend/src/main/java/core/repositories/timemanager/TaskRepository.java
+++ b/backend/src/main/java/core/repositories/timemanager/TaskRepository.java
@@ -8,10 +8,14 @@ import org.springframework.data.repository.CrudRepository;
 import org.springframework.stereotype.Repository;
 
 import javax.transaction.Transactional;
+import java.util.List;
 
 @Repository
 public interface TaskRepository extends CrudRepository<Task, Long> {
 
+    @Query(value = "SELECT t FROM Task t WHERE t.taskgroup.user.username = ?1 AND t.finished = ?2")
+    List<Task> findAllByUser(String username, boolean finished);
+
     @Transactional
     @Modifying
     @Query(value = "DELETE FROM Task t WHERE t.taskgroup = ?1")
diff --git a/backend/src/main/java/core/services/TaskScheduleService.java b/backend/src/main/java/core/services/TaskScheduleService.java
index 933dca4..b1fe601 100644
--- a/backend/src/main/java/core/services/TaskScheduleService.java
+++ b/backend/src/main/java/core/services/TaskScheduleService.java
@@ -1,6 +1,7 @@
 package core.services;
 
 import core.api.models.timemanager.taskSchedule.BasicTaskScheduleFieldInfo;
+import core.api.models.timemanager.taskSchedule.ForgottenActivity;
 import core.entities.User;
 import core.entities.timemanager.BasicTaskSchedule;
 import core.entities.timemanager.Task;
@@ -157,4 +158,59 @@ public class TaskScheduleService {
         }
         return false;
     }
+
+    public ServiceResult<Integer> registerForgottenActivity(Task task, ForgottenActivity forgottenActivity) {
+        switch (forgottenActivity.getMode()) {
+            case MANUAL -> {
+                task.increaseActiveTime(forgottenActivity.getMinutesSpent());
+                BasicTaskSchedule basicTaskSchedule = new BasicTaskSchedule(task, LocalDate.now());
+                LocalDateTime timeReference = LocalDateTime.now();
+                basicTaskSchedule.setStartTime(timeReference.minusMinutes(forgottenActivity.getMinutesSpent()));
+                basicTaskSchedule.setFinishedTime(timeReference);
+                task.getBasicTaskSchedules().add(basicTaskSchedule);
+                basicTaskScheduleRepository.save(basicTaskSchedule);
+                taskRepository.save(task);
+                return new ServiceResult<>(forgottenActivity.getMinutesSpent());
+            }
+            case LAST -> {
+                List<BasicTaskSchedule> schedules = basicTaskScheduleRepository.findAllFinishedByUserAndDate(task.getTaskgroup().getUser(), LocalDate.now());
+                if(schedules.isEmpty()) {
+                    return new ServiceResult<>(ServiceExitCode.INVALID_OPERATION);
+                } else {
+                    LocalDateTime timeReference = LocalDateTime.now();
+                    BasicTaskSchedule nearestSchedule = null;
+                    long nearestDuration = Long.MAX_VALUE;
+                    for(BasicTaskSchedule schedule : schedules) {
+                        if(nearestSchedule == null) {
+                            nearestSchedule = schedule;
+                            nearestDuration = Duration.between(nearestSchedule.getFinishedTime(), timeReference).getSeconds();
+                        } else {
+                            long currentDuration = Duration.between(schedule.getFinishedTime(), timeReference).getSeconds();
+                            if(currentDuration < nearestDuration) {
+                                nearestSchedule = schedule;
+                                nearestDuration = currentDuration;
+                            }
+                        }
+                    }
+
+                    int minutesSpent = (int) Duration.between(nearestSchedule.getFinishedTime(), timeReference).toMinutes();
+                    task.increaseActiveTime(minutesSpent);
+                    BasicTaskSchedule basicTaskSchedule = new BasicTaskSchedule(task, timeReference.toLocalDate());
+                    basicTaskSchedule.setStartTime(nearestSchedule.getFinishedTime());
+                    basicTaskSchedule.setFinishedTime(timeReference);
+                    basicTaskScheduleRepository.save(basicTaskSchedule);
+                    taskRepository.save(task);
+                    return new ServiceResult<>(minutesSpent);
+                }
+            }
+            case PLANNED -> {
+                //Does not make sense until advanced schedule/moderate schedule is implemented
+                return new ServiceResult<>(0);
+            }
+            default -> {
+                throw new RuntimeException("INVALID MODE");
+            }
+        }
+
+    }
 }
diff --git a/backend/src/main/java/core/services/TaskService.java b/backend/src/main/java/core/services/TaskService.java
index 7a31773..7a300fa 100644
--- a/backend/src/main/java/core/services/TaskService.java
+++ b/backend/src/main/java/core/services/TaskService.java
@@ -98,4 +98,8 @@ public class TaskService {
             taskScheduleService.deleteBasicSchedule(deletedTaskSchedule);
         }
     }
+
+    public List<Task> loadAllTasks(String username, boolean finished) {
+        return taskRepository.findAllByUser(username, finished);
+    }
 }
diff --git a/frontend/src/api/.openapi-generator/FILES b/frontend/src/api/.openapi-generator/FILES
index f2b32bb..e0272ae 100644
--- a/frontend/src/api/.openapi-generator/FILES
+++ b/frontend/src/api/.openapi-generator/FILES
@@ -17,6 +17,7 @@ model/accountDeleteRequest.ts
 model/basicScheduleEntityInfo.ts
 model/basicScheduleFieldInfo.ts
 model/eMailChangeRequest.ts
+model/forgottenActivityRequest.ts
 model/inlineResponse200.ts
 model/inlineResponse401.ts
 model/inlineResponse403.ts
diff --git a/frontend/src/api/api/schedule.service.ts b/frontend/src/api/api/schedule.service.ts
index 41cc133..da226af 100644
--- a/frontend/src/api/api/schedule.service.ts
+++ b/frontend/src/api/api/schedule.service.ts
@@ -20,6 +20,7 @@ import { Observable }                                        from 'rxjs';
 
 import { BasicScheduleEntityInfo } from '../model/models';
 import { BasicScheduleFieldInfo } from '../model/models';
+import { ForgottenActivityRequest } from '../model/models';
 import { ScheduleActivateInfo } from '../model/models';
 import { ScheduleInfo } from '../model/models';
 import { ScheduleStatus } from '../model/models';
@@ -581,6 +582,76 @@ export class ScheduleService {
         );
     }
 
+    /**
+     * registers forgotten schedule
+     * Registers forgotten schedule
+     * @param taskID internal id of task
+     * @param forgottenActivityRequest 
+     * @param observe set whether or not to return the data Observable as the body, response or events. defaults to returning the body.
+     * @param reportProgress flag to report request and response progress.
+     */
+    public schedulesTaskIDForgottenPost(taskID: number, forgottenActivityRequest?: ForgottenActivityRequest, observe?: 'body', reportProgress?: boolean, options?: {httpHeaderAccept?: 'application/json', context?: HttpContext}): Observable<TaskScheduleStopResponse>;
+    public schedulesTaskIDForgottenPost(taskID: number, forgottenActivityRequest?: ForgottenActivityRequest, observe?: 'response', reportProgress?: boolean, options?: {httpHeaderAccept?: 'application/json', context?: HttpContext}): Observable<HttpResponse<TaskScheduleStopResponse>>;
+    public schedulesTaskIDForgottenPost(taskID: number, forgottenActivityRequest?: ForgottenActivityRequest, observe?: 'events', reportProgress?: boolean, options?: {httpHeaderAccept?: 'application/json', context?: HttpContext}): Observable<HttpEvent<TaskScheduleStopResponse>>;
+    public schedulesTaskIDForgottenPost(taskID: number, forgottenActivityRequest?: ForgottenActivityRequest, observe: any = 'body', reportProgress: boolean = false, options?: {httpHeaderAccept?: 'application/json', context?: HttpContext}): Observable<any> {
+        if (taskID === null || taskID === undefined) {
+            throw new Error('Required parameter taskID was null or undefined when calling schedulesTaskIDForgottenPost.');
+        }
+
+        let localVarHeaders = this.defaultHeaders;
+
+        let localVarCredential: string | undefined;
+        // authentication (API_TOKEN) required
+        localVarCredential = this.configuration.lookupCredential('API_TOKEN');
+        if (localVarCredential) {
+            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
+        }
+
+        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
+        if (localVarHttpHeaderAcceptSelected === undefined) {
+            // to determine the Accept header
+            const httpHeaderAccepts: string[] = [
+                'application/json'
+            ];
+            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
+        }
+        if (localVarHttpHeaderAcceptSelected !== undefined) {
+            localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
+        }
+
+        let localVarHttpContext: HttpContext | undefined = options && options.context;
+        if (localVarHttpContext === undefined) {
+            localVarHttpContext = new HttpContext();
+        }
+
+
+        // to determine the Content-Type header
+        const consumes: string[] = [
+            'application/json'
+        ];
+        const httpContentTypeSelected: string | undefined = this.configuration.selectHeaderContentType(consumes);
+        if (httpContentTypeSelected !== undefined) {
+            localVarHeaders = localVarHeaders.set('Content-Type', httpContentTypeSelected);
+        }
+
+        let responseType_: 'text' | 'json' = 'json';
+        if(localVarHttpHeaderAcceptSelected && localVarHttpHeaderAcceptSelected.startsWith('text')) {
+            responseType_ = 'text';
+        }
+
+        return this.httpClient.post<TaskScheduleStopResponse>(`${this.configuration.basePath}/schedules/${encodeURIComponent(String(taskID))}/forgotten`,
+            forgottenActivityRequest,
+            {
+                context: localVarHttpContext,
+                responseType: <any>responseType_,
+                withCredentials: this.configuration.withCredentials,
+                headers: localVarHeaders,
+                observe: observe,
+                reportProgress: reportProgress
+            }
+        );
+    }
+
     /**
      * schedule task now
      * schedule task now
diff --git a/frontend/src/api/api/task.service.ts b/frontend/src/api/api/task.service.ts
index 69a7362..549949d 100644
--- a/frontend/src/api/api/task.service.ts
+++ b/frontend/src/api/api/task.service.ts
@@ -22,6 +22,7 @@ import { InlineResponse403 } from '../model/models';
 import { SimpleStatusResponse } from '../model/models';
 import { TaskEntityInfo } from '../model/models';
 import { TaskFieldInfo } from '../model/models';
+import { TaskShortInfo } from '../model/models';
 
 import { BASE_PATH, COLLECTION_FORMATS }                     from '../variables';
 import { Configuration }                                     from '../configuration';
@@ -88,6 +89,65 @@ export class TaskService {
         return httpParams;
     }
 
+    /**
+     * edits an existing task
+     * edits an existing task
+     * @param finished fetches either finished or unfinished tasks
+     * @param observe set whether or not to return the data Observable as the body, response or events. defaults to returning the body.
+     * @param reportProgress flag to report request and response progress.
+     */
+    public tasksAllFinishedGet(finished: boolean, observe?: 'body', reportProgress?: boolean, options?: {httpHeaderAccept?: 'application/json', context?: HttpContext}): Observable<Array<TaskShortInfo>>;
+    public tasksAllFinishedGet(finished: boolean, observe?: 'response', reportProgress?: boolean, options?: {httpHeaderAccept?: 'application/json', context?: HttpContext}): Observable<HttpResponse<Array<TaskShortInfo>>>;
+    public tasksAllFinishedGet(finished: boolean, observe?: 'events', reportProgress?: boolean, options?: {httpHeaderAccept?: 'application/json', context?: HttpContext}): Observable<HttpEvent<Array<TaskShortInfo>>>;
+    public tasksAllFinishedGet(finished: boolean, observe: any = 'body', reportProgress: boolean = false, options?: {httpHeaderAccept?: 'application/json', context?: HttpContext}): Observable<any> {
+        if (finished === null || finished === undefined) {
+            throw new Error('Required parameter finished was null or undefined when calling tasksAllFinishedGet.');
+        }
+
+        let localVarHeaders = this.defaultHeaders;
+
+        let localVarCredential: string | undefined;
+        // authentication (API_TOKEN) required
+        localVarCredential = this.configuration.lookupCredential('API_TOKEN');
+        if (localVarCredential) {
+            localVarHeaders = localVarHeaders.set('Authorization', 'Bearer ' + localVarCredential);
+        }
+
+        let localVarHttpHeaderAcceptSelected: string | undefined = options && options.httpHeaderAccept;
+        if (localVarHttpHeaderAcceptSelected === undefined) {
+            // to determine the Accept header
+            const httpHeaderAccepts: string[] = [
+                'application/json'
+            ];
+            localVarHttpHeaderAcceptSelected = this.configuration.selectHeaderAccept(httpHeaderAccepts);
+        }
+        if (localVarHttpHeaderAcceptSelected !== undefined) {
+            localVarHeaders = localVarHeaders.set('Accept', localVarHttpHeaderAcceptSelected);
+        }
+
+        let localVarHttpContext: HttpContext | undefined = options && options.context;
+        if (localVarHttpContext === undefined) {
+            localVarHttpContext = new HttpContext();
+        }
+
+
+        let responseType_: 'text' | 'json' = 'json';
+        if(localVarHttpHeaderAcceptSelected && localVarHttpHeaderAcceptSelected.startsWith('text')) {
+            responseType_ = 'text';
+        }
+
+        return this.httpClient.get<Array<TaskShortInfo>>(`${this.configuration.basePath}/tasks/all/${encodeURIComponent(String(finished))}`,
+            {
+                context: localVarHttpContext,
+                responseType: <any>responseType_,
+                withCredentials: this.configuration.withCredentials,
+                headers: localVarHeaders,
+                observe: observe,
+                reportProgress: reportProgress
+            }
+        );
+    }
+
     /**
      * edits an existing task
      * edits an existing task
diff --git a/frontend/src/api/model/forgottenActivityRequest.ts b/frontend/src/api/model/forgottenActivityRequest.ts
new file mode 100644
index 0000000..46085b4
--- /dev/null
+++ b/frontend/src/api/model/forgottenActivityRequest.ts
@@ -0,0 +1,33 @@
+/**
+ * API Title
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 1.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+export interface ForgottenActivityRequest { 
+    /**
+     * mode of register forgotten activity
+     */
+    mode: ForgottenActivityRequest.ModeEnum;
+    /**
+     * number of minutes spent on task
+     */
+    minutesSpent?: number;
+}
+export namespace ForgottenActivityRequest {
+    export type ModeEnum = 'MANUAL' | 'LAST' | 'PLANNED';
+    export const ModeEnum = {
+        Manual: 'MANUAL' as ModeEnum,
+        Last: 'LAST' as ModeEnum,
+        Planned: 'PLANNED' as ModeEnum
+    };
+}
+
+
diff --git a/frontend/src/api/model/models.ts b/frontend/src/api/model/models.ts
index 008265d..030f3a8 100644
--- a/frontend/src/api/model/models.ts
+++ b/frontend/src/api/model/models.ts
@@ -2,6 +2,7 @@ export * from './accountDeleteRequest';
 export * from './basicScheduleEntityInfo';
 export * from './basicScheduleFieldInfo';
 export * from './eMailChangeRequest';
+export * from './forgottenActivityRequest';
 export * from './inlineResponse200';
 export * from './inlineResponse401';
 export * from './inlineResponse403';
diff --git a/frontend/src/app/app.module.ts b/frontend/src/app/app.module.ts
index a9d9233..468aec4 100644
--- a/frontend/src/app/app.module.ts
+++ b/frontend/src/app/app.module.ts
@@ -67,6 +67,8 @@ import { ActiveScheduleComponent } from './dashboard/active-schedule/active-sche
 import {MatTreeModule} from "@angular/material/tree";
 import { TaskgroupOverviewComponent } from './dashboard/taskgroup-overview/taskgroup-overview.component';
 import { TaskOverviewComponent } from './dashboard/task-overview/task-overview.component';
+import { ForgottenTaskStartDialogComponent } from './dashboard/forgotten-task-start-dialog/forgotten-task-start-dialog.component';
+import {MatAutocompleteModule} from "@angular/material/autocomplete";
 @NgModule({
   declarations: [
     AppComponent,
@@ -97,44 +99,46 @@ import { TaskOverviewComponent } from './dashboard/task-overview/task-overview.c
     DashboardComponent,
     ActiveScheduleComponent,
     TaskgroupOverviewComponent,
-    TaskOverviewComponent
+    TaskOverviewComponent,
+    ForgottenTaskStartDialogComponent
+  ],
+  imports: [
+    BrowserModule,
+    AppRoutingModule,
+    FormsModule,
+    ApiModule,
+    HttpClientModule,
+    BrowserAnimationsModule,
+    MatToolbarModule,
+    MatButtonModule,
+    MatIconModule,
+    MatDialogModule,
+    MatFormFieldModule,
+    MatInputModule,
+    MatProgressSpinnerModule,
+    MatSnackBarModule,
+    MatMenuModule,
+    MatTabsModule,
+    MatTableModule,
+    MatCheckboxModule,
+    MatCardModule,
+    ReactiveFormsModule,
+    MatListModule,
+    MatDatepickerModule,
+    MatInputModule,
+    MatDatepickerModule,
+    MatMomentDateModule,
+    FormsModule,
+    MatSlideToggleModule,
+    MatSortModule,
+    MatPaginatorModule,
+    MatProgressBarModule,
+    MatExpansionModule,
+    CalendarModule.forRoot({provide: DateAdapter, useFactory: adapterFactory}),
+    MatSelectModule,
+    MatTreeModule,
+    MatAutocompleteModule
   ],
-    imports: [
-        BrowserModule,
-        AppRoutingModule,
-        FormsModule,
-        ApiModule,
-        HttpClientModule,
-        BrowserAnimationsModule,
-        MatToolbarModule,
-        MatButtonModule,
-        MatIconModule,
-        MatDialogModule,
-        MatFormFieldModule,
-        MatInputModule,
-        MatProgressSpinnerModule,
-        MatSnackBarModule,
-        MatMenuModule,
-        MatTabsModule,
-        MatTableModule,
-        MatCheckboxModule,
-        MatCardModule,
-        ReactiveFormsModule,
-        MatListModule,
-        MatDatepickerModule,
-        MatInputModule,
-        MatDatepickerModule,
-        MatMomentDateModule,
-        FormsModule,
-        MatSlideToggleModule,
-        MatSortModule,
-        MatPaginatorModule,
-        MatProgressBarModule,
-        MatExpansionModule,
-        CalendarModule.forRoot({provide: DateAdapter, useFactory: adapterFactory}),
-        MatSelectModule,
-        MatTreeModule
-    ],
   providers: [
     HttpClientModule,
     /*
diff --git a/frontend/src/app/dashboard/active-schedule/active-schedule.component.html b/frontend/src/app/dashboard/active-schedule/active-schedule.component.html
index b793d84..a7d1ee1 100644
--- a/frontend/src/app/dashboard/active-schedule/active-schedule.component.html
+++ b/frontend/src/app/dashboard/active-schedule/active-schedule.component.html
@@ -1,7 +1,7 @@
 <mat-card class="green-card" *ngIf="activeSchedule == undefined">
   <mat-card-content>
     <p>Currently there is no task in progress.</p>
-    <a class="btn-link" routerLink="/">Did you forget to start an activity?</a>
+    <a class="btn-link" (click)="openForgettedActivityDialog()">Did you forget to start an activity?</a>
   </mat-card-content>
 </mat-card>
 <mat-card *ngIf="activeSchedule != undefined">
diff --git a/frontend/src/app/dashboard/active-schedule/active-schedule.component.ts b/frontend/src/app/dashboard/active-schedule/active-schedule.component.ts
index 69dd31c..cd36f86 100644
--- a/frontend/src/app/dashboard/active-schedule/active-schedule.component.ts
+++ b/frontend/src/app/dashboard/active-schedule/active-schedule.component.ts
@@ -1,7 +1,9 @@
 import {Component, EventEmitter, Input, OnInit, Output} from '@angular/core';
-import {ScheduleInfo, ScheduleService, TaskOverviewInfo} from "../../../api";
+import {ScheduleInfo, ScheduleService, TaskOverviewInfo, TaskScheduleStopResponse} from "../../../api";
 import {StopActiveScheduleInfo} from "./StopActiveScheduleInfo";
 import {TaskOverviewComponent} from "../task-overview/task-overview.component";
+import {MatDialog} from "@angular/material/dialog";
+import {ForgottenTaskStartDialogComponent} from "../forgotten-task-start-dialog/forgotten-task-start-dialog.component";
 
 @Component({
   selector: 'app-active-schedule',
@@ -16,8 +18,10 @@ export class ActiveScheduleComponent implements OnInit{
   displayTime: string = "00:00:00"
 
   @Output('onStopTask') scheduleStopEmitter = new EventEmitter<StopActiveScheduleInfo>;
+  @Output('registerForgotten') registerForgottenEmitter = new EventEmitter<TaskScheduleStopResponse>
 
-  constructor(private scheduleService: ScheduleService) {
+  constructor(private scheduleService: ScheduleService,
+              private dialog: MatDialog) {
 
 
   }
@@ -74,4 +78,12 @@ export class ActiveScheduleComponent implements OnInit{
     this.activeSchedule = undefined
   }
 
+  openForgettedActivityDialog() {
+    const dialogRef = this.dialog.open(ForgottenTaskStartDialogComponent, {width: "400px"})
+    dialogRef.afterClosed().subscribe(res => {
+      if(res != undefined) {
+        this.registerForgottenEmitter.emit(res);
+      }
+    })
+  }
 }
diff --git a/frontend/src/app/dashboard/dashboard.component.html b/frontend/src/app/dashboard/dashboard.component.html
index 90d9742..54db53e 100644
--- a/frontend/src/app/dashboard/dashboard.component.html
+++ b/frontend/src/app/dashboard/dashboard.component.html
@@ -8,7 +8,7 @@
     </mat-card>
     <h1 class="dashboard-heading">Now<b class="today-worked-info">Today: {{workedMinutesToday}} min</b></h1>
 
-    <app-active-schedule #activeSchedule (onStopTask)="stopedTask($event)"></app-active-schedule>
+    <app-active-schedule #activeSchedule (onStopTask)="stopedTask($event)" (registerForgotten)="registerForgotten($event)"></app-active-schedule>
 
     <h1 class="dashboard-heading">Scheduled for today</h1>
     <mat-card class="green-card" *ngIf="schedules.length == 0">
diff --git a/frontend/src/app/dashboard/dashboard.component.ts b/frontend/src/app/dashboard/dashboard.component.ts
index f09a3d8..a012bd1 100644
--- a/frontend/src/app/dashboard/dashboard.component.ts
+++ b/frontend/src/app/dashboard/dashboard.component.ts
@@ -1,5 +1,11 @@
 import {Component, OnInit, ViewChild} from '@angular/core';
-import {BasicScheduleEntityInfo, ScheduleInfo, ScheduleService, TaskOverviewInfo} from "../../api";
+import {
+  BasicScheduleEntityInfo,
+  ScheduleInfo,
+  ScheduleService,
+  TaskOverviewInfo,
+  TaskScheduleStopResponse
+} from "../../api";
 import {ActiveScheduleComponent} from "./active-schedule/active-schedule.component";
 import {StopActiveScheduleInfo} from "./active-schedule/StopActiveScheduleInfo";
 import {TaskOverviewComponent} from "./task-overview/task-overview.component";
@@ -72,4 +78,8 @@ export class DashboardComponent implements OnInit{
 
     this.schedules = this.schedules.filter(schedule => schedule.task.taskID !== task.taskID)
   }
+
+  registerForgotten(taskScheduleStopResponse: TaskScheduleStopResponse) {
+    this.workedMinutesToday += taskScheduleStopResponse.workTime
+  }
 }
diff --git a/frontend/src/app/dashboard/forgotten-task-start-dialog/forgotten-task-start-dialog.component.css b/frontend/src/app/dashboard/forgotten-task-start-dialog/forgotten-task-start-dialog.component.css
new file mode 100644
index 0000000..ad2c300
--- /dev/null
+++ b/frontend/src/app/dashboard/forgotten-task-start-dialog/forgotten-task-start-dialog.component.css
@@ -0,0 +1,4 @@
+.example-full-width {
+  width: 100%;
+  margin-left: 10px;
+}
diff --git a/frontend/src/app/dashboard/forgotten-task-start-dialog/forgotten-task-start-dialog.component.html b/frontend/src/app/dashboard/forgotten-task-start-dialog/forgotten-task-start-dialog.component.html
new file mode 100644
index 0000000..f2b9df2
--- /dev/null
+++ b/frontend/src/app/dashboard/forgotten-task-start-dialog/forgotten-task-start-dialog.component.html
@@ -0,0 +1,31 @@
+<h1 mat-dialog-title>Register forgotten activity</h1>
+<div mat-dialog-content>
+  <mat-form-field class="example-full-width">
+    <mat-label>Number</mat-label>
+    <input type="text"
+           placeholder="Pick one"
+           matInput
+           [formControl]="myControl"
+           [matAutocomplete]="auto">
+    <mat-autocomplete autoActiveFirstOption #auto="matAutocomplete">
+      <mat-option *ngFor="let option of filteredOptions | async" [value]="option">
+        {{option}}
+      </mat-option>
+    </mat-autocomplete>
+  </mat-form-field>
+
+  <mat-checkbox *ngIf="!plannedSchedule" [(ngModel)]="lastSchedule">Automatic starttime based on <b>last</b> schedule</mat-checkbox>
+  <mat-checkbox *ngIf="!lastSchedule" [(ngModel)]="plannedSchedule">Automatic starttime based on <b>planned</b> schedule</mat-checkbox>
+
+  <mat-form-field class="example-full-width" *ngIf="!lastSchedule && !plannedSchedule">
+    <mat-label>Minutes spent</mat-label>
+    <input matInput type="number" [formControl]="minutesSpentControl">
+  </mat-form-field>
+</div>
+
+<div mat-dialog-actions align="end">
+  <button mat-raised-button>Cancel</button>
+  <button mat-raised-button color="primary" (click)="registerActivity()">Register</button>
+</div>
+
+
diff --git a/frontend/src/app/dashboard/forgotten-task-start-dialog/forgotten-task-start-dialog.component.spec.ts b/frontend/src/app/dashboard/forgotten-task-start-dialog/forgotten-task-start-dialog.component.spec.ts
new file mode 100644
index 0000000..756a4e9
--- /dev/null
+++ b/frontend/src/app/dashboard/forgotten-task-start-dialog/forgotten-task-start-dialog.component.spec.ts
@@ -0,0 +1,21 @@
+import { ComponentFixture, TestBed } from '@angular/core/testing';
+
+import { ForgottenTaskStartDialogComponent } from './forgotten-task-start-dialog.component';
+
+describe('ForgottenTaskStartDialogComponent', () => {
+  let component: ForgottenTaskStartDialogComponent;
+  let fixture: ComponentFixture<ForgottenTaskStartDialogComponent>;
+
+  beforeEach(() => {
+    TestBed.configureTestingModule({
+      declarations: [ForgottenTaskStartDialogComponent]
+    });
+    fixture = TestBed.createComponent(ForgottenTaskStartDialogComponent);
+    component = fixture.componentInstance;
+    fixture.detectChanges();
+  });
+
+  it('should create', () => {
+    expect(component).toBeTruthy();
+  });
+});
diff --git a/frontend/src/app/dashboard/forgotten-task-start-dialog/forgotten-task-start-dialog.component.ts b/frontend/src/app/dashboard/forgotten-task-start-dialog/forgotten-task-start-dialog.component.ts
new file mode 100644
index 0000000..5cc7abf
--- /dev/null
+++ b/frontend/src/app/dashboard/forgotten-task-start-dialog/forgotten-task-start-dialog.component.ts
@@ -0,0 +1,87 @@
+import {Component, OnInit} from '@angular/core';
+import {ForgottenActivityRequest, ScheduleService, TaskService, TaskShortInfo} from "../../../api";
+import {MatSnackBar} from "@angular/material/snack-bar";
+import {DialogRef} from "@angular/cdk/dialog";
+import {MatDialogRef} from "@angular/material/dialog";
+import {filter, map, Observable, startWith} from "rxjs";
+import {FormControl} from "@angular/forms";
+import ModeEnum = ForgottenActivityRequest.ModeEnum;
+
+@Component({
+  selector: 'app-forgotten-task-start-dialog',
+  templateUrl: './forgotten-task-start-dialog.component.html',
+  styleUrls: ['./forgotten-task-start-dialog.component.css']
+})
+export class ForgottenTaskStartDialogComponent implements OnInit{
+
+  tasks: TaskShortInfo[] = []
+  myControl: FormControl = new FormControl('');
+  filteredOptions: Observable<string[]> | undefined;
+
+  lastSchedule: boolean = false
+  plannedSchedule: boolean = false
+  minutesSpentControl: FormControl = new FormControl();
+
+
+  constructor(private taskService: TaskService,
+              private snackbar: MatSnackBar,
+              private dialogRef: MatDialogRef<ForgottenTaskStartDialogComponent>,
+              private scheduleService: ScheduleService) {
+  }
+
+  ngOnInit() {
+    this.taskService.tasksAllFinishedGet(false).subscribe({
+      next: resp => {
+        this.tasks = resp;
+        this.filteredOptions = this.myControl.valueChanges.pipe(
+          startWith(''),
+          map(value => this._filter(value || '')),
+        );
+      },
+      error: err =>  {
+        this.snackbar.open("Unexpected error", "", {duration: 2000});
+      }
+    })
+  }
+
+  private _filter(value: string): string[] {
+    const filterValue = value.toLowerCase();
+
+    return this.tasks.map(x => x.taskName).filter(option => option.toLowerCase().includes(filterValue))
+  }
+
+  registerActivity() {
+    const task = this.tasks.find(task => task.taskName === this.myControl.value);
+    if(task != undefined) {
+      this.scheduleService.schedulesTaskIDForgottenPost(task.taskID, {
+        mode: this.determineRegisterMode(),
+        minutesSpent: this.minutesSpentControl.value
+      }).subscribe({
+        next: resp => {
+          this.dialogRef.close(resp);
+        },
+        error: err => {
+          if(err.status == 400) {
+            this.snackbar.open("Invalid Operation", "", {duration: 2000});
+          } else if(err.status == 403) {
+            this.snackbar.open("No permission", "", {duration: 2000});
+          } else if(err.status == 404) {
+            this.snackbar.open("Task not found", "", {duration: 2000});
+          } else {
+            this.snackbar.open("Unexpected error", "", {duration: 2000});
+          }
+        }
+      })
+    }
+  }
+
+  private determineRegisterMode(): ModeEnum {
+    if(this.lastSchedule) {
+      return "LAST";
+    } else if(this.plannedSchedule) {
+      return "PLANNED";
+    } else {
+      return "MANUAL";
+    }
+  }
+}
diff --git a/openapi.yaml b/openapi.yaml
index 19ab60b..06c21fd 100644
--- a/openapi.yaml
+++ b/openapi.yaml
@@ -883,6 +883,32 @@ paths:
               schema:
                 type: object
                 $ref: "#/components/schemas/SimpleStatusResponse"    
+  /tasks/all/{finished}:
+    get:
+      security:
+        - API_TOKEN: []
+      tags:
+        - task
+      summary: edits an existing task
+      description: edits an existing task
+      parameters:
+        - name: finished
+          in: path
+          description: fetches either finished or unfinished tasks
+          required: true
+          schema:
+            type: boolean
+            example: true
+      responses:
+        200:
+          description: Operation successfull
+          content:
+            application/json:
+              schema:
+                type: array
+                items:
+                  $ref: '#/components/schemas/TaskShortInfo'
+
   /tasks/{taskgroupID}/{status}:
     get: 
       security:
@@ -1619,7 +1645,55 @@ paths:
               schema:
                 type: object
                 $ref: "#/components/schemas/SimpleStatusResponse"
-      
+  /schedules/{taskID}/forgotten:
+    post:
+      security:
+        - API_TOKEN: []
+      tags:
+        - schedule
+      description: Registers forgotten schedule
+      summary: registers forgotten schedule
+      parameters:
+        - name: taskID
+          in: path
+          description: internal id of task
+          required: true
+          schema:
+            type: number
+            example: 1
+      requestBody:
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/ForgottenActivityRequest'
+      responses:
+        200:
+          description: Operation successfull
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/TaskScheduleStopResponse'
+        403:
+          description: No permission
+          content:
+            'application/json':
+              schema:
+                type: object
+                $ref: "#/components/schemas/SimpleStatusResponse"
+        404:
+          description: Schedule does not exist
+          content:
+            'application/json':
+              schema:
+                type: object
+                $ref: "#/components/schemas/SimpleStatusResponse"
+        400:
+          description: Operation not valid
+          content:
+            'application/json':
+              schema:
+                type: object
+                $ref: "#/components/schemas/SimpleStatusResponse"
       
       
       
@@ -2140,4 +2214,21 @@ components:
         missedSchedules:
           type: boolean
           description: states whether a schedule was missed or not
-          example: true
\ No newline at end of file
+          example: true
+    ForgottenActivityRequest:
+      required:
+        - mode
+      additionalProperties: false
+      properties:
+        mode:
+          type: string
+          description: mode of register forgotten activity
+          example: MANUAL
+          enum:
+            - MANUAL
+            - LAST
+            - PLANNED
+        minutesSpent:
+          type: number
+          description: number of minutes spent on task
+          example: 10
\ No newline at end of file