diff --git a/src/bot/commands/task.ts b/src/bot/commands/task.ts
index 8ac63ce..630684b 100644
--- a/src/bot/commands/task.ts
+++ b/src/bot/commands/task.ts
@@ -1,6 +1,7 @@
 import { sendMessage } from '../utils/messaging';
 import { createTask, assignTask, completeTask, getPendingTasks } from '../../services/taskService';
 import { setRemindersEnabled } from '../../services/userService';
+import { normalizeUserIdentifier, extractUserFromJid } from '../../utils/userUtils';
 
 function formatTaskList(tasks: any[]) {
   if (tasks.length === 0) {
diff --git a/src/services/notificationService.ts b/src/services/notificationService.ts
new file mode 100644
index 0000000..90214fa
--- /dev/null
+++ b/src/services/notificationService.ts
@@ -0,0 +1,54 @@
+import { sendMessage } from '../utils/messaging';
+import { formatUserMention } from '../utils/userUtils';
+import { Task } from '../models/task';
+
+export function notifyTaskCreation(task: Task) {
+  const creatorMention = formatUserMention(task.createdBy);
+  const assigneeMention = task.assignedTo ? formatUserMention(task.assignedTo) : 'ninguno';
+  
+  // Notify creator
+  let message = `✅ Tarea creada:\nID: ${task.id}\nDescripción: ${task.description}`;
+  if (task.assignedTo) {
+    message += `\nAsignada a: ${assigneeMention}`;
+  }
+  if (task.dueDate) {
+    message += `\nFecha límite: ${task.dueDate}`;
+  }
+  sendMessage(task.createdBy, message);
+
+  // Notify assignee if different from creator
+  if (task.assignedTo && task.assignedTo !== task.createdBy) {
+    const assigneeMessage = `📝 ${creatorMention} te ha asignado una nueva tarea:\n` +
+      `ID: ${task.id}\nDescripción: ${task.description}` +
+      (task.dueDate ? `\nFecha límite: ${task.dueDate}` : '');
+    sendMessage(task.assignedTo, assigneeMessage);
+  }
+}
+
+export function notifyTaskAssignment(task: Task, assignedBy: string) {
+  const assignerMention = formatUserMention(assignedBy);
+  const assigneeMention = formatUserMention(task.assignedTo);
+
+  // Notify assigner
+  sendMessage(assignedBy, `✅ Tarea ${task.id} asignada a ${assigneeMention}`);
+
+  // Notify assignee
+  const assigneeMessage = `📝 ${assignerMention} te ha asignado la tarea:\n` +
+    `ID: ${task.id}\nDescripción: ${task.description}` +
+    (task.dueDate ? `\nFecha límite: ${task.dueDate}` : '');
+  sendMessage(task.assignedTo, assigneeMessage);
+}
+
+export function notifyTaskCompletion(task: Task, completedBy: string) {
+  const completerMention = formatUserMention(completedBy);
+
+  // Notify completer
+  sendMessage(completedBy, `✅ Tarea completada:\nID: ${task.id}\nDescripción: ${task.description}`);
+
+  // Notify creator if different from completer
+  if (task.createdBy && task.createdBy !== completedBy) {
+    const creatorMessage = `✅ ${completerMention} ha completado la tarea:\n` +
+      `ID: ${task.id}\nDescripción: ${task.description}`;
+    sendMessage(task.createdBy, creatorMessage);
+  }
+}
diff --git a/src/services/taskService.ts b/src/services/taskService.ts
index eb32b63..6130392 100644
--- a/src/services/taskService.ts
+++ b/src/services/taskService.ts
@@ -1,7 +1,11 @@
 import { query, execute } from '../database/db';
+import { normalizeUserIdentifier } from '../utils/userUtils';
+import { notifyTaskCreation, notifyTaskAssignment, notifyTaskCompletion } from './notificationService';
 
 // Create a new task
 export function createTask(sender: string, params: CreateTaskParams) {
+  const createdBy = normalizeUserIdentifier(sender);
+  const assignedTo = params.assignedTo ? normalizeUserIdentifier(params.assignedTo) : null;
   if (!params.description || params.description.trim().length < 3) {
     throw new Error('La descripción de la tarea debe tener al menos 3 caracteres');
   }
@@ -12,13 +16,16 @@ export function createTask(sender: string, params: CreateTaskParams) {
 
   const result = execute(
     'INSERT INTO tasks (description, created_by, assigned_to, due_date, completed) VALUES (?, ?, ?, ?, ?)',
-    [params.description.trim(), sender, params.assignedTo || null, params.dueDate || null, false]
+    [params.description.trim(), createdBy, assignedTo, params.dueDate || null, false]
   );
 
   const task = getTaskById(result.lastInsertRowid);
   if (!task) {
     throw new Error('Error al crear la tarea');
   }
+  
+  // Notify relevant users
+  notifyTaskCreation(task);
   return task;
 }
 
diff --git a/src/utils/userUtils.ts b/src/utils/userUtils.ts
new file mode 100644
index 0000000..f26c867
--- /dev/null
+++ b/src/utils/userUtils.ts
@@ -0,0 +1,24 @@
+export function normalizeUserIdentifier(input: string): string {
+  // Remove @ prefix if present
+  const cleanInput = input.startsWith('@') ? input.slice(1) : input;
+  
+  // Remove any non-numeric characters
+  const phoneNumber = cleanInput.replace(/\D/g, '');
+  
+  // Validate phone number length
+  if (phoneNumber.length < 8 || phoneNumber.length > 15) {
+    throw new Error('Número de teléfono inválido');
+  }
+  
+  return `@${phoneNumber}`;
+}
+
+export function extractUserFromJid(jid: string): string {
+  // Extract phone number from JID (format: 12345678@s.whatsapp.net)
+  const phoneNumber = jid.split('@')[0];
+  return normalizeUserIdentifier(phoneNumber);
+}
+
+export function formatUserMention(phoneNumber: string): string {
+  return `@${phoneNumber.replace('@', '')}`;
+}