diff --git a/addons/project/models/project.py b/addons/project/models/project.py
index e02dcf8fac5..642fb37e62c 100644
--- a/addons/project/models/project.py
+++ b/addons/project/models/project.py
@@ -223,6 +223,9 @@ class Project(models.Model):
     doc_count = fields.Integer(compute='_compute_attached_docs_count', string="Number of documents attached")
     date_start = fields.Date(string='Start Date')
     date = fields.Date(string='Expiration Date', index=True, track_visibility='onchange')
+    subtask_project_id = fields.Many2one('project.project', string='Sub-task Project', ondelete="restrict",
+        help="Choosing a sub-tasks project will both enable sub-tasks and set their default project (possibly the project itself)")
+
     # rating fields
     percentage_satisfaction_task = fields.Integer(
         compute='_compute_percentage_satisfaction_task', string="Happy % on Task", store=True, default=-1)
@@ -299,6 +302,8 @@ class Project(models.Model):
         # Prevent double project creation
         self = self.with_context(mail_create_nosubscribe=True)
         project = super(Project, self).create(vals)
+        if not vals.get('subtask_project_id'):
+            project.subtask_project_id = project.id
         if project.privacy_visibility == 'portal' and project.partner_id:
             project.message_subscribe(project.partner_id.ids)
         return project
@@ -528,6 +533,7 @@ class Task(models.Model):
     legend_normal = fields.Char(related='stage_id.legend_normal', string='Kanban Ongoing Explanation', readonly=True, related_sudo=False)
     parent_id = fields.Many2one('project.task', string='Parent Task', index=True)
     child_ids = fields.One2many('project.task', 'parent_id', string="Sub-tasks", context={'active_test': False})
+    subtask_project_id = fields.Many2one('project.project', related="project_id.subtask_project_id", string='Sub-task Project', readonly=True)
     subtask_count = fields.Integer("Sub-task count", compute='_compute_subtask_count')
     email_from = fields.Char(string='Email', help="These people will receive email.", index=True)
     email_cc = fields.Char(string='Watchers Emails', help="""These email addresses will be added to the CC field of all inbound
diff --git a/addons/project/views/project_views.xml b/addons/project/views/project_views.xml
index 41dad0fef65..bdc686a873e 100644
--- a/addons/project/views/project_views.xml
+++ b/addons/project/views/project_views.xml
@@ -140,6 +140,7 @@
                                 </div>
                                 <field name="rating_status_period"  class="oe_inline" attrs="{'required': [('rating_status','=','periodic')], 'invisible': [('rating_status','!=','periodic')]}" groups="project.group_project_rating"/>
                                 <field name="portal_show_rating" attrs="{'invisible': [('rating_status','==','no')]}" groups="project.group_project_rating"/>
+                                <field name="subtask_project_id" groups="project.group_subtask_project"/>
                             </group>
                             <group name="misc">
                                 <group string="Configuration" groups="base.group_no_one">
@@ -418,7 +419,7 @@
                         <button class="oe_stat_button" icon="fa-tasks" type="object" name="action_open_parent_task" string="Parent Task" attrs="{'invisible' : [('parent_id', '=', False)]}" groups="project.group_subtask_project"/>
                         <button name="action_subtask" type="object" class="oe_stat_button" icon="fa-tasks"
                             attrs="{'invisible' : [('parent_id', '!=', False)]}"
-                            context="{'project_id': project_id, 'name': name, 'parent_id': id}" groups="project.group_subtask_project">
+                            context="{'project_id': subtask_project_id, 'name': name, 'partner_id': partner_id}" groups="project.group_subtask_project">
                             <field string="Sub-tasks" name="subtask_count" widget="statinfo"/>
                         </button>
                         <button name="%(rating_rating_action_task)d" type="action" attrs="{'invisible': [('rating_count', '=', 0)]}" class="oe_stat_button" icon="fa-smile-o" groups="project.group_project_rating">
@@ -466,6 +467,7 @@
                                     <field name="email_cc" groups="base.group_no_one"/>
                                     <field name="parent_id" attrs="{'invisible' : [('subtask_count', '>', 0)]}" groups="project.group_subtask_project"/>
                                     <field name="child_ids" invisible="1" />
+                                    <field name="subtask_project_id" invisible="1" />
                                     <field name="company_id" groups="base.group_multi_company" options="{'no_create': True}"/>
                                     <field name="displayed_image_id" groups="base.group_no_one"/>
                                 </group>