diff --git a/.docker_files/main/__manifest__.py b/.docker_files/main/__manifest__.py
index 24bba5c..6a404dd 100644
--- a/.docker_files/main/__manifest__.py
+++ b/.docker_files/main/__manifest__.py
@@ -13,6 +13,7 @@
     "depends": [
         "hr_timesheet_project_parent_enhanced",
         "project_timesheet_time_control_sheet",
+        "timesheet_task_project_no_change",
     ],
     "installable": True,
 }
diff --git a/Dockerfile b/Dockerfile
index caef0b0..13dc86d 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -12,6 +12,7 @@ USER odoo
 
 COPY hr_timesheet_project_parent_enhanced  /mnt/extra-addons/hr_timesheet_project_parent_enhanced
 COPY project_timesheet_time_control_sheet  /mnt/extra-addons/project_timesheet_time_control_sheet
+COPY timesheet_task_project_no_change  /mnt/extra-addons/timesheet_task_project_no_change 
 
 COPY .docker_files/main /mnt/extra-addons/main
 COPY .docker_files/odoo.conf /etc/odoo
diff --git a/timesheet_task_project_no_change/README.rst b/timesheet_task_project_no_change/README.rst
new file mode 100644
index 0000000..7569ffe
--- /dev/null
+++ b/timesheet_task_project_no_change/README.rst
@@ -0,0 +1,23 @@
+Timesheet Task Project No Change
+================================
+
+Usage
+-----
+
+As a user of the **Project** module, when attempting to change the project of a task:
+
+1. If timesheets have already been recorded on the task, a blocking message will appear:
+   
+   .. image:: static/description/task_timesheet_error.png
+      :alt: Blocking error when task has timesheets
+
+2. If timesheets have been recorded on a subtask, a similar blocking message will appear:
+   
+   .. image:: static/description/subtask_timesheet_error.png
+      :alt: Blocking error when subtask has timesheets
+
+3. In both cases, the task's project cannot be changed unless no timesheets exist for the task or its subtasks.
+
+Contributors
+------------
+* Numigi (tm) and all its contributors (https://bit.ly/numigiens)
diff --git a/timesheet_task_project_no_change/__init__.py b/timesheet_task_project_no_change/__init__.py
new file mode 100644
index 0000000..efb1fef
--- /dev/null
+++ b/timesheet_task_project_no_change/__init__.py
@@ -0,0 +1,4 @@
+# Copyright 2024 - today Numigi (tm) and all its contributors (https://bit.ly/numigiens)
+# License LGPL-3.0 or later (http://www.gnu.org/licenses/lgpl).
+
+from . import models
diff --git a/timesheet_task_project_no_change/__manifest__.py b/timesheet_task_project_no_change/__manifest__.py
new file mode 100644
index 0000000..2109075
--- /dev/null
+++ b/timesheet_task_project_no_change/__manifest__.py
@@ -0,0 +1,15 @@
+# Copyright 2024 - today Numigi (tm) and all its contributors (https://bit.ly/numigiens)
+# License LGPL-3.0 or later (http://www.gnu.org/licenses/lgpl).
+
+{
+    "name": "Timesheet Task Project No Change",
+    "version": "16.0.1.0.0",
+    "author": "Numigi",
+    "maintainer": "Numigi",
+    "website": "https://bit.ly/numigi-com",
+    "license": "LGPL-3",
+    "category": "Project",
+    "summary": "Prevent changing the project on a task with timesheets.",
+    "depends": ["hr_timesheet"],
+    "installable": True,
+}
diff --git a/timesheet_task_project_no_change/i18n/fr.po b/timesheet_task_project_no_change/i18n/fr.po
new file mode 100644
index 0000000..25f0541
--- /dev/null
+++ b/timesheet_task_project_no_change/i18n/fr.po
@@ -0,0 +1,47 @@
+# Translation of Odoo Server.
+# This file contains the translation of the following modules:
+# 	* timesheet_task_project_no_change
+#
+msgid ""
+msgstr ""
+"Project-Id-Version: Odoo Server 16.0\n"
+"Report-Msgid-Bugs-To: \n"
+"POT-Creation-Date: 2024-12-03 11:49+0000\n"
+"PO-Revision-Date: 2024-12-03 11:49+0000\n"
+"Last-Translator: \n"
+"Language-Team: \n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: \n"
+"Plural-Forms: \n"
+
+#. module: timesheet_task_project_no_change
+#: model:ir.model,name:timesheet_task_project_no_change.model_project_task
+msgid "Task"
+msgstr "Tâche"
+
+#. module: timesheet_task_project_no_change
+#. odoo-python
+#: code:addons/timesheet_task_project_no_change/models/project_task.py:0
+#, python-format
+msgid ""
+"Timesheets have already been entered on a sub-task ({subtask}). In order to "
+"modify the project of the parent task ({task}), there must be no time on the"
+" parent task, nor on its child tasks."
+msgstr ""
+"Du temps a été saisi une des tâches enfant ({subtask}). Pour modifier le "
+"projet de la tâche parente ({task}), il ne doit pas y avoir de temps saisi "
+"sur celle-ci ou sur ses tâches enfants."
+
+#. module: timesheet_task_project_no_change
+#. odoo-python
+#: code:addons/timesheet_task_project_no_change/models/project_task.py:0
+#, python-format
+msgid ""
+"Timesheets have already been entered on this task ({task}). In order to "
+"modify the project of this task, you may close the task and create another "
+"in the target project."
+msgstr ""
+"Du temps a déjà été saisi sur la tâche ({task}). Pour modifier le projet de "
+"la tâche, veuillez fermer celle-ci et en créer une nouvelle sur le projet "
+"cible."
diff --git a/timesheet_task_project_no_change/models/__init__.py b/timesheet_task_project_no_change/models/__init__.py
new file mode 100644
index 0000000..022d5ba
--- /dev/null
+++ b/timesheet_task_project_no_change/models/__init__.py
@@ -0,0 +1,4 @@
+# Copyright 2024 - today Numigi (tm) and all its contributors (https://bit.ly/numigiens)
+# License LGPL-3.0 or later (http://www.gnu.org/licenses/lgpl).
+
+from . import project_task
diff --git a/timesheet_task_project_no_change/models/project_task.py b/timesheet_task_project_no_change/models/project_task.py
new file mode 100644
index 0000000..4a0ce64
--- /dev/null
+++ b/timesheet_task_project_no_change/models/project_task.py
@@ -0,0 +1,50 @@
+# Copyright 2024 - today Numigi (tm) and all its contributors (https://bit.ly/numigiens)
+# License LGPL-3.0 or later (http://www.gnu.org/licenses/lgpl).
+
+from odoo import models, _
+from odoo.exceptions import ValidationError
+
+
+class ProjectTask(models.Model):
+    _inherit = "project.task"
+
+    def write(self, vals):
+        if "project_id" in vals:
+            project = self.env["project.project"].browse(vals["project_id"])
+            tasks_with_different_project = self.filtered(
+                lambda t: t.project_id != project
+            )
+
+            for task in tasks_with_different_project:
+                task._validate_no_timesheets()
+                task._validate_no_subtask_timesheets()
+
+        return super().write(vals)
+
+    def _validate_no_timesheets(self):
+        if self.sudo().timesheet_ids:
+            raise ValidationError(
+                _(
+                    "Timesheets have already been entered on this task ({task}). "
+                    "In order to modify the project of this task, you may "
+                    "close the task and create another in the target project."
+                ).format(task=self.display_name)
+            )
+
+    def _validate_no_subtask_timesheets(self):
+        timesheets = (
+            self.env["account.analytic.line"]
+            .sudo()
+            .search([("task_id.parent_id", "=", self.id)])
+        )
+
+        if timesheets:
+            raise ValidationError(
+                _(
+                    "Timesheets have already been entered on a sub-task ({subtask}). "
+                    "In order to modify the project of the parent task ({task}), there must "
+                    "be no time on the parent task, nor on its child tasks."
+                ).format(
+                    task=self.display_name, subtask=timesheets[0].task_id.display_name
+                )
+            )
diff --git a/timesheet_task_project_no_change/static/description/icon.png b/timesheet_task_project_no_change/static/description/icon.png
new file mode 100644
index 0000000..92a86b1
Binary files /dev/null and b/timesheet_task_project_no_change/static/description/icon.png differ
diff --git a/timesheet_task_project_no_change/static/description/subtask_timesheet_error.png b/timesheet_task_project_no_change/static/description/subtask_timesheet_error.png
new file mode 100644
index 0000000..acf3855
Binary files /dev/null and b/timesheet_task_project_no_change/static/description/subtask_timesheet_error.png differ
diff --git a/timesheet_task_project_no_change/static/description/task_timesheet_error.png b/timesheet_task_project_no_change/static/description/task_timesheet_error.png
new file mode 100644
index 0000000..4427027
Binary files /dev/null and b/timesheet_task_project_no_change/static/description/task_timesheet_error.png differ
diff --git a/timesheet_task_project_no_change/tests/__init__.py b/timesheet_task_project_no_change/tests/__init__.py
new file mode 100644
index 0000000..ad0d160
--- /dev/null
+++ b/timesheet_task_project_no_change/tests/__init__.py
@@ -0,0 +1,4 @@
+# Copyright 2024 - today Numigi (tm) and all its contributors (https://bit.ly/numigiens)
+# License LGPL-3.0 or later (http://www.gnu.org/licenses/lgpl).
+
+from . import test_project_task
diff --git a/timesheet_task_project_no_change/tests/test_project_task.py b/timesheet_task_project_no_change/tests/test_project_task.py
new file mode 100644
index 0000000..80952d0
--- /dev/null
+++ b/timesheet_task_project_no_change/tests/test_project_task.py
@@ -0,0 +1,51 @@
+# Copyright 2024 - today Numigi (tm) and all its contributors (https://bit.ly/numigiens)
+# License LGPL-3.0 or later (http://www.gnu.org/licenses/lgpl).
+
+import pytest
+from odoo.exceptions import ValidationError
+from odoo.tests.common import TransactionCase
+
+
+class TestProjectTask(TransactionCase):
+    @classmethod
+    def setUpClass(cls):
+        super().setUpClass()
+        cls.project_a = cls.env["project.project"].create({"name": "projectA"})
+        cls.project_b = cls.env["project.project"].create({"name": "projectB"})
+        cls.task = cls.env["project.task"].create(
+            {"name": "Parent Task", "project_id": cls.project_a.id}
+        )
+        cls.subtask = cls.env["project.task"].create(
+            {
+                "name": "Child Task",
+                "project_id": cls.project_a.id,
+                "parent_id": cls.task.id,
+            }
+        )
+
+    def test_if_no_timesheet__project_can_be_changed(self):
+        self.task.project_id = self.project_b
+
+    def test_if_project_is_the_same__constraint_not_raised(self):
+        self._make_timesheet_line(self.task)
+        self.task.project_id = self.project_a
+
+    def test_if_task_has_timesheet__project_can_not_be_changed(self):
+        self._make_timesheet_line(self.task)
+        with pytest.raises(ValidationError):
+            self.task.project_id = self.project_b
+
+    def test_if_subtask_has_timesheet__project_can_not_be_changed(self):
+        self._make_timesheet_line(self.subtask)
+        with pytest.raises(ValidationError):
+            self.task.project_id = self.project_b
+
+    def _make_timesheet_line(self, task):
+        return self.env["account.analytic.line"].create(
+            {
+                "task_id": task.id,
+                "project_id": task.project_id.id,
+                "name": "/",
+                "employee_id": self.ref("hr.employee_admin"),
+            }
+        )