fix: net_amount calculation (#44231)

fix: tax_item_rate calculation

erpnext/controllers/accounts_controller.py

@@ -961,6 +961,7 @@ class AccountsController(TransactionBase):
 							"account_head": account_head,
 							"rate": 0,
 							"description": account_head,
+							"set_by_item_tax_template": 1,
 						},
 					)
 
@@ -3176,10 +3177,11 @@ def set_child_tax_template_and_map(item, child_item, parent_doc):
 	)
 
 	child_item.item_tax_template = _get_item_tax_template(ctx, item.taxes)
-	if child_item.get("item_tax_template"):
-		child_item.item_tax_rate = get_item_tax_map(
-			parent_doc.get("company"), child_item.item_tax_template, as_json=True
-		)
+	child_item.item_tax_rate = get_item_tax_map(
+		doc=parent_doc,
+		tax_template=child_item.item_tax_template,
+		as_json=True,
+	)
 
 
 def add_taxes_from_tax_template(child_item, parent_doc, db_insert=True):
@@ -3202,6 +3204,7 @@ def add_taxes_from_tax_template(child_item, parent_doc, db_insert=True):
 						"charge_type": "On Net Total",
 						"account_head": tax_type,
 						"rate": tax_rate,
+						"set_by_item_tax_template": 1,
 					}
 				)
 				if parent_doc.doctype == "Purchase Order":

erpnext/controllers/taxes_and_totals.py

@@ -501,9 +501,7 @@ class calculate_taxes_and_totals:
 				)
 
 		elif tax.charge_type == "On Net Total":
-			if not item_tax_map:
-				current_net_amount = item.net_amount
-			elif tax.account_head in item_tax_map:
+			if tax.account_head in item_tax_map:
 				current_net_amount = item.net_amount
 			current_tax_amount = (tax_rate / 100.0) * item.net_amount
 		elif tax.charge_type == "On Previous Row Amount":

erpnext/controllers/tests/test_item_wise_tax_details.py

@@ -79,7 +79,7 @@ class TestTaxesAndTotals(FrappeTestCase):
 				"rate": 50,
 			},
 		)
-
+		self.doc.set_missing_item_details()
 		calculate_taxes_and_totals(self.doc)
 
 		expected_values = {