diff --git a/allow_negative_leave_and_allocation/models/__init__.py b/allow_negative_leave_and_allocation/models/__init__.py
index ed1f735..fd469c5 100644
--- a/allow_negative_leave_and_allocation/models/__init__.py
+++ b/allow_negative_leave_and_allocation/models/__init__.py
@@ -1 +1 @@
-from . import hr_leave_type, hr_leave
\ No newline at end of file
+from . import hr_leave_type, hr_leave, hr_leave_allocation
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diff --git a/allow_negative_leave_and_allocation/models/hr_leave_allocation.py b/allow_negative_leave_and_allocation/models/hr_leave_allocation.py
new file mode 100644
index 0000000..09ef58f
--- /dev/null
+++ b/allow_negative_leave_and_allocation/models/hr_leave_allocation.py
@@ -0,0 +1,19 @@
+# -*- coding: utf-8 -*-
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+
+# Copyright (c) 2005-2006 Axelor SARL. (http://www.axelor.com)
+
+from odoo import models
+
+class HrLeaveAllocation(models.Model):
+    _inherit = "hr.leave.allocation"
+
+    _sql_constraints = [
+        ('type_value',
+         "CHECK( (holiday_type='employee' AND (employee_id IS NOT NULL OR multi_employee IS TRUE)) or "
+         "(holiday_type='category' AND category_id IS NOT NULL) or "
+         "(holiday_type='department' AND department_id IS NOT NULL) or "
+         "(holiday_type='company' AND mode_company_id IS NOT NULL))",
+         "The employee, department, company or employee category of this request is missing. Please make sure that your user login is linked to an employee."),
+        ('duration_check', "CHECK((allocation_type != 'regular'))", "The duration must be greater than 0."),
+    ]
\ No newline at end of file