diff --git a/erpnext/accounts/doctype/c_form/c_form.js b/erpnext/accounts/doctype/c_form/c_form.js
index 4a90a9d..6629de6 100644
--- a/erpnext/accounts/doctype/c_form/c_form.js
+++ b/erpnext/accounts/doctype/c_form/c_form.js
@@ -1,7 +1,7 @@
 //c-form js file
 // -----------------------------
 cur_frm.fields_dict.invoice_details.grid.get_field("invoice_no").get_query = function(doc) {
-	return 'SELECT `tabReceivable Voucher`.`name` FROM `tabReceivable Voucher` WHERE `tabReceivable Voucher`.`company` = "' +doc.company+'" AND `tabReceivable Voucher`.%(key)s LIKE "%s" AND `tabReceivable Voucher`.`customer` = "' + doc.customer + '" AND `tabReceivable Voucher`.`docstatus` = 1 and `tabReceivable Voucher`.`c_form_applicable` = "Yes" ORDER BY `tabReceivable Voucher`.`name` ASC LIMIT 50';
+	return 'SELECT `tabReceivable Voucher`.`name` FROM `tabReceivable Voucher` WHERE `tabReceivable Voucher`.`company` = "' +doc.company+'" AND `tabReceivable Voucher`.%(key)s LIKE "%s" AND `tabReceivable Voucher`.`customer` = "' + doc.customer + '" AND `tabReceivable Voucher`.`docstatus` = 1 and `tabReceivable Voucher`.`c_form_applicable` = "Yes" and ifnull(`tabReceivable Voucher`.c_form_no, "") = "" ORDER BY `tabReceivable Voucher`.`name` ASC LIMIT 50';
 }
 
 cur_frm.cscript.invoice_no = function(doc, cdt, cdn) {
diff --git a/erpnext/accounts/doctype/c_form/c_form.py b/erpnext/accounts/doctype/c_form/c_form.py
index 00016cb..7228f11 100644
--- a/erpnext/accounts/doctype/c_form/c_form.py
+++ b/erpnext/accounts/doctype/c_form/c_form.py
@@ -17,12 +17,23 @@
 	def autoname(self):
 		self.doc.name = make_autoname(self.doc.naming_series + '.#####')
 
+
 	def on_update(self):
-		inv = "'" + "', '".join([d.invoice_no for d in getlist(self.doclist, 'invoice_details')]) + "'"
-		sql("""update `tabReceivable Voucher` set c_form_no = '%s', modified ='%s'
+		"""	Update C-Form No on invoices"""
+		
+		if len(getlist(self.doclist, 'invoice_details')):
+			inv = "'" + "', '".join([d.invoice_no for d in getlist(self.doclist, 'invoice_details')]) + "'"
+			sql("""update `tabReceivable Voucher` set c_form_no = '%s', modified ='%s'
 				where name in (%s)"""%(self.doc.name, self.doc.modified, inv))
+			sql("""update `tabReceivable Voucher` set c_form_no = '', modified = %s where name not
+				in (%s) and ifnull(c_form_no, '') = %s""", (self.doc.modified, self.doc.name, inv))
+		else:
+			msgprint("Please enter atleast 1 invoice in the table below", raise_exception=1)
+
 
 	def get_invoice_details(self, invoice_no):
+		"""	Pull details from invoices for referrence """
+
 		inv = sql("""select posting_date, territory, net_total, grand_total from
 			`tabReceivable Voucher` where name = %s""", invoice_no)	
 		ret = {
@@ -32,3 +43,19 @@
 			'grand_total'  : inv and flt(inv[0][3]) or ''
 		}
 		return ret
+
+
+	def validate_invoice(self):
+		"""Validate invoice that c-form is applicable and no other c-form is
+		received for that"""
+
+		for d in getlist(self.doclist, 'invoice_details'):
+			inv = sql("""select c_form_applicable, c_form_no from
+				`tabReceivable Voucher` where name = %s""", invoice_no)
+			if not inv:
+				msgprint("Invoice: %s is not exists in the system, please check." % d.invoice_no, raise_exception=1)
+			elif inv[0][0] != 'Yes':
+				msgprint("C-form is not applicable for Invoice: %s" % d.invoice_no, raise_exception=1)
+			elif inv[0][1] and inv[0][1] != self.doc.name:
+				msgprint("""Invoice %s is tagged in another C-form: %s. \nIf you want to change C-form no for this invoice,
+					please remove invoice no from the previous c-form and then try again""" % (d.invoice_no, inv[0][1]), raise_exception=1)
diff --git a/erpnext/accounts/doctype/receivable_voucher/receivable_voucher.js b/erpnext/accounts/doctype/receivable_voucher/receivable_voucher.js
index 363da2e..12b57d9 100644
--- a/erpnext/accounts/doctype/receivable_voucher/receivable_voucher.js
+++ b/erpnext/accounts/doctype/receivable_voucher/receivable_voucher.js
@@ -67,6 +67,12 @@
 			}
 		}
 	}
+
+	// India related fields
+	var cp = locals['Control Panel']['Control Panel'];
+	if (cp.country == 'India') unhide_field(['c_form_applicable', 'c_form_no']);
+	else hide_field(['c_form_applicable', 'c_form_no']);
+
 }