fix: calculate tds with net amount when invoice exceeds single threshold amount (backport #43869) (#43919)

* fix: calculate tds with net amount when invoice exceeds single threshold amount

(cherry picked from commit ef694a40a1)

* test: add unit test to validate purchase invoice exceeding single threshold value

(cherry picked from commit 94badb464d)

---------

Co-authored-by: venkat102 <venkatesharunachalam659@gmail.com>

erpnext/accounts/doctype/tax_withholding_category/tax_withholding_category.py

@@ -482,7 +482,7 @@ def get_tds_amount(ldc, parties, inv, tax_details, vouchers):
 		payment_entry_filters.pop("apply_tax_withholding_amount", None)
 		payment_entry_filters.pop("tax_withholding_category", None)
 
-	supp_credit_amt = frappe.db.get_value("Purchase Invoice", invoice_filters, field) or 0.0
+	supp_inv_credit_amt = frappe.db.get_value("Purchase Invoice", invoice_filters, field) or 0.0
 
 	supp_jv_credit_amt = (
 		frappe.db.get_value(
@@ -506,7 +506,7 @@ def get_tds_amount(ldc, parties, inv, tax_details, vouchers):
 		group_by="payment_type",
 	)
 
-	supp_credit_amt += supp_jv_credit_amt
+	supp_credit_amt = supp_jv_credit_amt
 	supp_credit_amt += inv.tax_withholding_net_total
 
 	for type in payment_entry_amounts:
@@ -524,18 +524,18 @@ def get_tds_amount(ldc, parties, inv, tax_details, vouchers):
 		tax_withholding_net_total = inv.tax_withholding_net_total
 
 	if (threshold and tax_withholding_net_total >= threshold) or (
-		cumulative_threshold and supp_credit_amt >= cumulative_threshold
+		cumulative_threshold and (supp_credit_amt + supp_inv_credit_amt) >= cumulative_threshold
 	):
+		# Get net total again as TDS is calculated on net total
+		# Grand is used to just check for threshold breach
+		net_total = (
+			frappe.db.get_value("Purchase Invoice", invoice_filters, "sum(tax_withholding_net_total)") or 0.0
+		)
+		supp_credit_amt += net_total
+
 		if (cumulative_threshold and supp_credit_amt >= cumulative_threshold) and cint(
 			tax_details.tax_on_excess_amount
 		):
-			# Get net total again as TDS is calculated on net total
-			# Grand is used to just check for threshold breach
-			net_total = (
-				frappe.db.get_value("Purchase Invoice", invoice_filters, "sum(tax_withholding_net_total)")
-				or 0.0
-			)
-			net_total += inv.tax_withholding_net_total
 			supp_credit_amt = net_total - cumulative_threshold
 
 		if ldc and is_valid_certificate(ldc, inv.get("posting_date") or inv.get("transaction_date"), 0):

erpnext/accounts/doctype/tax_withholding_category/test_tax_withholding_category.py

@@ -121,6 +121,46 @@ class TestTaxWithholdingCategory(FrappeTestCase):
 		for d in reversed(invoices):
 			d.cancel()
 
+	def test_cumulative_threshold_with_party_ledger_amount_on_net_total(self):
+		invoices = []
+		frappe.db.set_value(
+			"Supplier", "Test TDS Supplier3", "tax_withholding_category", "Advance TDS Category"
+		)
+
+		# Invoice with tax and without exceeding single and cumulative thresholds
+		for _ in range(2):
+			pi = create_purchase_invoice(supplier="Test TDS Supplier3", rate=1000, do_not_save=True)
+			pi.apply_tds = 1
+			pi.append(
+				"taxes",
+				{
+					"category": "Total",
+					"charge_type": "Actual",
+					"account_head": "_Test Account VAT - _TC",
+					"cost_center": "Main - _TC",
+					"tax_amount": 500,
+					"description": "Test",
+					"add_deduct_tax": "Add",
+				},
+			)
+			pi.save()
+			pi.submit()
+			invoices.append(pi)
+
+		# Third Invoice exceeds single threshold and not exceeding cumulative threshold
+		pi1 = create_purchase_invoice(supplier="Test TDS Supplier3", rate=6000)
+		pi1.apply_tds = 1
+		pi1.save()
+		pi1.submit()
+		invoices.append(pi1)
+
+		# Cumulative threshold is 10,000
+		# Threshold calculation should be only on the third invoice
+		self.assertEqual(pi1.taxes[0].tax_amount, 800)
+
+		for d in reversed(invoices):
+			d.cancel()
+
 	def test_cumulative_threshold_tcs(self):
 		frappe.db.set_value(
 			"Customer", "Test TCS Customer", "tax_withholding_category", "Cumulative Threshold TCS"