diff --git a/erpnext/hooks.py b/erpnext/hooks.py
index b4c57d7..741176f 100644
--- a/erpnext/hooks.py
+++ b/erpnext/hooks.py
@@ -237,6 +237,9 @@
 	"Website Settings": {
 		"validate": "erpnext.portal.doctype.products_settings.products_settings.home_page_is_products"
 	},
+	"Tax Category": {
+		"validate": "erpnext.regional.india.utils.validate_tax_category"
+	},
 	"Sales Invoice": {
 		"on_submit": [
 			"erpnext.regional.create_transaction_log",
diff --git a/erpnext/regional/india/utils.py b/erpnext/regional/india/utils.py
index fc38ed0..62487ba 100644
--- a/erpnext/regional/india/utils.py
+++ b/erpnext/regional/india/utils.py
@@ -51,6 +51,13 @@
 			frappe.throw(_("Invalid GSTIN! First 2 digits of GSTIN should match with State number {0}.")
 				.format(doc.gst_state_number))
 
+def validate_tax_category(doc, method):
+	if doc.get('gst_state') and frappe.db.get_value('Tax category', {'gst_state': doc.gst_state, 'is_inter_state': doc.is_inter_state}):
+		if doc.is_inter_state:
+			frappe.throw(_("Inter State tax category for GST State {0} already exists").format(doc.gst_state))
+		else:
+			frappe.throw(_("Intra State tax category for GST State {0} already exists").format(doc.gst_state))
+
 def update_gst_category(doc, method):
 	for link in doc.links:
 		if link.link_doctype in ['Customer', 'Supplier']:
@@ -85,8 +92,7 @@
 		total += digit
 		factor = 2 if factor == 1 else 1
 	if gstin[-1] != code_point_chars[((mod - (total % mod)) % mod)]:
-		frappe.throw(_("""Invalid {0}! The check digit validation has failed.
-			Please ensure you've typed the {0} correctly.""").format(label))
+		frappe.throw(_("""Invalid {0}! The check digit validation has failed. Please ensure you've typed the {0} correctly.""").format(label))
 
 def get_itemised_tax_breakup_header(item_doctype, tax_accounts):
 	if frappe.get_meta(item_doctype).has_field('gst_hsn_code'):
@@ -515,7 +521,7 @@
 		data.transType = 1
 		data.actualToStateCode = data.toStateCode
 		shipping_address = billing_address
-	
+
 	if doc.gst_category == 'SEZ':
 		data.toStateCode = 99
 
@@ -754,4 +760,4 @@
 					}, account_currency, item=tax)
 				)
 
-	return gl_entries
\ No newline at end of file
+	return gl_entries