diff --git a/erpnext/hr/doctype/leave_allocation/leave_allocation.json b/erpnext/hr/doctype/leave_allocation/leave_allocation.json
index ae02c51..ae009ba 100644
--- a/erpnext/hr/doctype/leave_allocation/leave_allocation.json
+++ b/erpnext/hr/doctype/leave_allocation/leave_allocation.json
@@ -110,6 +110,7 @@
    "label": "Allocation"
   },
   {
+    "allow_on_submit": 1,
    "bold": 1,
    "fieldname": "new_leaves_allocated",
    "fieldtype": "Float",
@@ -235,7 +236,7 @@
  "index_web_pages_for_search": 1,
  "is_submittable": 1,
  "links": [],
- "modified": "2021-04-14 15:28:26.335104",
+ "modified": "2021-06-03 15:28:26.335104",
  "modified_by": "Administrator",
  "module": "HR",
  "name": "Leave Allocation",
@@ -277,4 +278,4 @@
  "sort_field": "modified",
  "sort_order": "DESC",
  "timeline_field": "employee"
-}
\ No newline at end of file
+}
diff --git a/erpnext/hr/doctype/leave_allocation/leave_allocation.py b/erpnext/hr/doctype/leave_allocation/leave_allocation.py
index 11302ca..4757cd3 100755
--- a/erpnext/hr/doctype/leave_allocation/leave_allocation.py
+++ b/erpnext/hr/doctype/leave_allocation/leave_allocation.py
@@ -8,6 +8,7 @@
 from frappe.model.document import Document
 from erpnext.hr.utils import set_employee_name, get_leave_period
 from erpnext.hr.doctype.leave_ledger_entry.leave_ledger_entry import expire_allocation, create_leave_ledger_entry
+from erpnext.hr.doctype.leave_application.leave_application import get_approved_leaves_for_period
 
 class OverlapError(frappe.ValidationError): pass
 class BackDatedAllocationError(frappe.ValidationError): pass
@@ -55,6 +56,43 @@
 		if self.carry_forward:
 			self.set_carry_forwarded_leaves_in_previous_allocation(on_cancel=True)
 
+	def on_update_after_submit(self):
+		if self.has_value_changed("new_leaves_allocated"):
+			self.validate_against_leave_applications()
+			leaves_to_be_added = self.new_leaves_allocated - self.get_existing_leave_count()
+			args = {
+				"leaves": leaves_to_be_added,
+				"from_date": self.from_date,
+				"to_date": self.to_date,
+				"is_carry_forward": 0
+			}
+			create_leave_ledger_entry(self, args, True)
+
+	def get_existing_leave_count(self):
+		ledger_entries = frappe.get_all("Leave Ledger Entry",
+								filters={
+									"transaction_type": "Leave Allocation",
+									"transaction_name": self.name,
+									"employee": self.employee,
+									"company": self.company,
+									"leave_type": self.leave_type
+								},
+								pluck="leaves")
+		total_existing_leaves = 0
+		for entry in ledger_entries:
+			total_existing_leaves += entry
+
+		return total_existing_leaves
+
+	def validate_against_leave_applications(self):
+		leaves_taken = get_approved_leaves_for_period(self.employee, self.leave_type,
+			self.from_date, self.to_date)
+		if flt(leaves_taken) > flt(self.total_leaves_allocated):
+			if frappe.db.get_value("Leave Type", self.leave_type, "allow_negative"):
+				frappe.msgprint(_("Note: Total allocated leaves {0} shouldn't be less than already approved leaves {1} for the period").format(self.total_leaves_allocated, leaves_taken))
+			else:
+				frappe.throw(_("Total allocated leaves {0} cannot be less than already approved leaves {1} for the period").format(self.total_leaves_allocated, leaves_taken), LessAllocationError)
+
 	def update_leave_policy_assignments_when_no_allocations_left(self):
 		allocations = frappe.db.get_list("Leave Allocation", filters = {
 			"docstatus": 1,
@@ -225,4 +263,4 @@
 
 def validate_carry_forward(leave_type):
 	if not frappe.db.get_value("Leave Type", leave_type, "is_carry_forward"):
-		frappe.throw(_("Leave Type {0} cannot be carry-forwarded").format(leave_type))
\ No newline at end of file
+		frappe.throw(_("Leave Type {0} cannot be carry-forwarded").format(leave_type))
diff --git a/erpnext/hr/doctype/leave_allocation/test_leave_allocation.py b/erpnext/hr/doctype/leave_allocation/test_leave_allocation.py
index 6e7ae87..49dd701 100644
--- a/erpnext/hr/doctype/leave_allocation/test_leave_allocation.py
+++ b/erpnext/hr/doctype/leave_allocation/test_leave_allocation.py
@@ -1,10 +1,10 @@
 from __future__ import unicode_literals
 import frappe
+import erpnext
 import unittest
 from frappe.utils import nowdate, add_months, getdate, add_days
 from erpnext.hr.doctype.leave_type.test_leave_type import create_leave_type
 from erpnext.hr.doctype.leave_ledger_entry.leave_ledger_entry import process_expired_allocation, expire_allocation
-
 class TestLeaveAllocation(unittest.TestCase):
 	@classmethod
 	def setUpClass(cls):
@@ -164,6 +164,53 @@
 		leave_allocation.cancel()
 		self.assertFalse(frappe.db.exists("Leave Ledger Entry", {'transaction_name':leave_allocation.name}))
 
+
+	def test_leave_addition_after_submit(self):
+		frappe.db.sql("delete from `tabLeave Allocation`")
+		frappe.db.sql("delete from `tabLeave Ledger Entry`")
+
+		leave_allocation = create_leave_allocation()
+		leave_allocation.submit()
+		self.assertTrue(leave_allocation.total_leaves_allocated, 15)
+		leave_allocation.new_leaves_allocated = 40
+		leave_allocation.submit()
+		self.assertTrue(leave_allocation.total_leaves_allocated, 40)
+
+	def test_leave_subtraction_after_submit(self):
+		frappe.db.sql("delete from `tabLeave Allocation`")
+		frappe.db.sql("delete from `tabLeave Ledger Entry`")
+
+		leave_allocation = create_leave_allocation()
+		leave_allocation.submit()
+		self.assertTrue(leave_allocation.total_leaves_allocated, 15)
+		leave_allocation.new_leaves_allocated = 10
+		leave_allocation.submit()
+		self.assertTrue(leave_allocation.total_leaves_allocated, 10)
+
+	def test_against_leave_application_validation_after_submit(self):
+		frappe.db.sql("delete from `tabLeave Allocation`")
+		frappe.db.sql("delete from `tabLeave Ledger Entry`")
+
+		leave_allocation = create_leave_allocation()
+		leave_allocation.submit()
+		self.assertTrue(leave_allocation.total_leaves_allocated, 15)
+		employee = frappe.get_doc("Employee", frappe.db.sql_list("select name from tabEmployee limit 1")[0])
+		leave_application = frappe.get_doc({
+			"doctype": 'Leave Application',
+			"employee": employee.name,
+			"leave_type": "_Test Leave Type",
+			"from_date": nowdate(),
+			"to_date": add_days(nowdate(), 10),
+			"company": erpnext.get_default_company() or "_Test Company",
+			"docstatus": 1,
+			"status": "Approved",
+			"leave_approver": 'test@example.com'
+		})
+		leave_application.submit()
+		leave_allocation.new_leaves_allocated = 8
+		leave_allocation.total_leaves_allocated = 8
+		self.assertRaises(frappe.ValidationError, leave_allocation.submit)
+
 def create_leave_allocation(**args):
 	args = frappe._dict(args)
 
diff --git a/erpnext/hr/report/employee_leave_balance/employee_leave_balance.py b/erpnext/hr/report/employee_leave_balance/employee_leave_balance.py
index 4dd4570..b8953b3 100644
--- a/erpnext/hr/report/employee_leave_balance/employee_leave_balance.py
+++ b/erpnext/hr/report/employee_leave_balance/employee_leave_balance.py
@@ -178,7 +178,7 @@
 			is_carry_forward, is_expired
 		FROM `tabLeave Ledger Entry`
 		WHERE employee=%(employee)s AND leave_type=%(leave_type)s
-			AND docstatus=1 AND leaves>0
+			AND docstatus=1
 			AND (from_date between %(from_date)s AND %(to_date)s
 				OR to_date between %(from_date)s AND %(to_date)s
 				OR (from_date < %(from_date)s AND to_date > %(to_date)s))