diff --git a/erpnext/accounts/doctype/tax_withholding_category/tax_withholding_category.py b/erpnext/accounts/doctype/tax_withholding_category/tax_withholding_category.py
index 09db7fe..5c1cbaa 100644
--- a/erpnext/accounts/doctype/tax_withholding_category/tax_withholding_category.py
+++ b/erpnext/accounts/doctype/tax_withholding_category/tax_withholding_category.py
@@ -21,7 +21,10 @@
 	else:
 		party_type = 'Supplier'
 		party = inv.supplier
-	
+
+	if not party:
+		frappe.throw(_("Please select {0} first").format(party_type))
+
 	return party_type, party
 
 def get_party_tax_withholding_details(inv, tax_withholding_category=None):
@@ -324,7 +327,7 @@
 		net_total, ldc.certificate_limit
 	):
 		tds_amount = get_ltds_amount(net_total, limit_consumed, ldc.certificate_limit, ldc.rate, tax_details)
-	
+
 	return tds_amount
 
 def get_debit_note_amount(suppliers, fiscal_year_details, company=None):