minor fixes
diff --git a/erpnext/erpnext_integrations/doctype/taxjar_settings/taxjar_settings.py b/erpnext/erpnext_integrations/doctype/taxjar_settings/taxjar_settings.py
index e03a2ac..725a61a 100644
--- a/erpnext/erpnext_integrations/doctype/taxjar_settings/taxjar_settings.py
+++ b/erpnext/erpnext_integrations/doctype/taxjar_settings/taxjar_settings.py
@@ -39,10 +39,10 @@
 				frappe.enqueue('erpnext.regional.united_states.setup.add_product_tax_categories', now=False)
 
 			elif fields_already_exist and fields_hidden:
-				toggle_tax_category_fields('1')
+				toggle_tax_category_fields(hidden='1')
 
-		elif not TAXJAR_CREATE_TRANSACTIONS and not TAXJAR_CALCULATE_TAX and not TAXJAR_SANDBOX_MODE:
-				toggle_tax_category_fields('0')
+		else:
+			toggle_tax_category_fields(hidden='0')
 
 	@frappe.whitelist()
 	def update_nexus_list(self):
@@ -55,9 +55,9 @@
 		self.set('nexus', new_nexus_list)
 		self.save()
 
-def toggle_tax_category_fields(toggle):
-	frappe.set_value('Custom Field',{'dt':'Sales Invoice Item', 'fieldname':'product_tax_category'},'hidden',toggle)
-	frappe.set_value('Custom Field',{'dt':'Item', 'fieldname':'product_tax_category'},'hidden',toggle)
+def toggle_tax_category_fields(hidden):
+	frappe.set_value('Custom Field',{'dt':'Sales Invoice Item', 'fieldname':'product_tax_category'},'hidden',hidden)
+	frappe.set_value('Custom Field',{'dt':'Item', 'fieldname':'product_tax_category'},'hidden',hidden)
 
 
 def add_product_tax_categories():
@@ -67,14 +67,12 @@
 
 def create_tax_categories(data):
 	for d in data:
-		tax_category = frappe.new_doc('Product Tax Category')
-		tax_category.description = d.get("description")
-		tax_category.product_tax_code = d.get("product_tax_code")
-		tax_category.category_name = d.get("name")
-		try:
+		if not frappe.db.exists('Product Tax Category',{'product_tax_code':d.get('product_tax_code')}):
+			tax_category = frappe.new_doc('Product Tax Category')
+			tax_category.description = d.get("description")
+			tax_category.product_tax_code = d.get("product_tax_code")
+			tax_category.category_name = d.get("name")
 			tax_category.db_insert()
-		except frappe.DuplicateEntryError:
-			pass
 
 def make_custom_fields(update=True):
 	custom_fields = {