[fix] tax_rule.py args
diff --git a/erpnext/accounts/party.py b/erpnext/accounts/party.py
index ba7ae32..69f40f8 100644
--- a/erpnext/accounts/party.py
+++ b/erpnext/accounts/party.py
@@ -320,11 +320,15 @@
 	from erpnext.accounts.doctype.tax_rule.tax_rule import get_tax_template, get_party_details
 	args = {
 		party_type.lower(): party,
-		"customer_group":	customer_group,
-		"supplier_type":	supplier_type,
 		"company":			company
 	}
 
+	if customer_group:
+		args['customer_group'] = customer_group
+
+	if supplier_type:
+		args['supplier_type'] = supplier_type
+
 	if billing_address or shipping_address:
 		args.update(get_party_details(party, party_type, {"billing_address": billing_address, \
 			"shipping_address": shipping_address }))