fix: Tax withholding post LDC limit consumed (#36611)

* fix: Tax withholding post LDC limit consumed

* fix: LDC condition check

erpnext/accounts/doctype/tax_withholding_category/tax_withholding_category.py

@@ -262,14 +262,20 @@ def get_tax_amount(party_type, parties, inv, tax_details, posting_date, pan_no=N
 		if tax_deducted:
 			net_total = inv.tax_withholding_net_total
 			if ldc:
-				tax_amount = get_tds_amount_from_ldc(ldc, parties, tax_details, posting_date, net_total)
+				limit_consumed = get_limit_consumed(ldc, parties)
+				if is_valid_certificate(ldc, posting_date, limit_consumed):
+					tax_amount = get_lower_deduction_amount(
+						net_total, limit_consumed, ldc.certificate_limit, ldc.rate, tax_details
+					)
+				else:
+					tax_amount = net_total * tax_details.rate / 100 if net_total > 0 else 0
 			else:
 				tax_amount = net_total * tax_details.rate / 100 if net_total > 0 else 0
 
 			# once tds is deducted, not need to add vouchers in the invoice
 			voucher_wise_amount = {}
 		else:
-			tax_amount = get_tds_amount(ldc, parties, inv, tax_details, tax_deducted, vouchers)
+			tax_amount = get_tds_amount(ldc, parties, inv, tax_details, vouchers)
 
 	elif party_type == "Customer":
 		if tax_deducted:
@@ -416,7 +422,7 @@ def get_deducted_tax(taxable_vouchers, tax_details):
 	return sum(entries)
 
 
-def get_tds_amount(ldc, parties, inv, tax_details, tax_deducted, vouchers):
+def get_tds_amount(ldc, parties, inv, tax_details, vouchers):
 	tds_amount = 0
 	invoice_filters = {"name": ("in", vouchers), "docstatus": 1, "apply_tds": 1}
 
@@ -496,15 +502,10 @@ def get_tds_amount(ldc, parties, inv, tax_details, tax_deducted, vouchers):
 			net_total += inv.tax_withholding_net_total
 			supp_credit_amt = net_total - cumulative_threshold
 
-		if ldc and is_valid_certificate(
+		if ldc and is_valid_certificate(ldc, inv.get("posting_date") or inv.get("transaction_date"), 0):
-			ldc.valid_from,
+			tds_amount = get_lower_deduction_amount(
-			ldc.valid_upto,
+				supp_credit_amt, 0, ldc.certificate_limit, ldc.rate, tax_details
-			inv.get("posting_date") or inv.get("transaction_date"),
+			)
-			tax_deducted,
-			inv.tax_withholding_net_total,
-			ldc.certificate_limit,
-		):
-			tds_amount = get_ltds_amount(supp_credit_amt, 0, ldc.certificate_limit, ldc.rate, tax_details)
 		else:
 			tds_amount = supp_credit_amt * tax_details.rate / 100 if supp_credit_amt > 0 else 0
 
@@ -582,8 +583,7 @@ def get_invoice_total_without_tcs(inv, tax_details):
 	return inv.grand_total - tcs_tax_row_amount
 
 
-def get_tds_amount_from_ldc(ldc, parties, tax_details, posting_date, net_total):
+def get_limit_consumed(ldc, parties):
-	tds_amount = 0
 	limit_consumed = frappe.db.get_value(
 		"Purchase Invoice",
 		{
@@ -597,37 +597,29 @@ def get_tds_amount_from_ldc(ldc, parties, tax_details, posting_date, net_total):
 		"sum(tax_withholding_net_total)",
 	)
 
-	if is_valid_certificate(
+	return limit_consumed
-		ldc.valid_from, ldc.valid_upto, posting_date, limit_consumed, net_total, ldc.certificate_limit
+
+
+def get_lower_deduction_amount(
+	current_amount, limit_consumed, certificate_limit, rate, tax_details
 ):
-		tds_amount = get_ltds_amount(
+	if certificate_limit - flt(limit_consumed) - flt(current_amount) >= 0:
-			net_total, limit_consumed, ldc.certificate_limit, ldc.rate, tax_details
-		)
-
-	return tds_amount
-
-
-def get_ltds_amount(current_amount, deducted_amount, certificate_limit, rate, tax_details):
-	if certificate_limit - flt(deducted_amount) - flt(current_amount) >= 0:
 		return current_amount * rate / 100
 	else:
-		ltds_amount = certificate_limit - flt(deducted_amount)
+		ltds_amount = certificate_limit - flt(limit_consumed)
 		tds_amount = current_amount - ltds_amount
 
 		return ltds_amount * rate / 100 + tds_amount * tax_details.rate / 100
 
 
-def is_valid_certificate(
+def is_valid_certificate(ldc, posting_date, limit_consumed):
-	valid_from, valid_upto, posting_date, deducted_amount, current_amount, certificate_limit
+	available_amount = flt(ldc.certificate_limit) - flt(limit_consumed)
-):
+	if (
-	valid = False
+		getdate(ldc.valid_from) <= getdate(posting_date) <= getdate(ldc.valid_upto)
+	) and available_amount > 0:
+		return True
 
-	available_amount = flt(certificate_limit) - flt(deducted_amount)
+	return False
-
-	if (getdate(valid_from) <= getdate(posting_date) <= getdate(valid_upto)) and available_amount > 0:
-		valid = True
-
-	return valid
 
 
 def normal_round(number):

erpnext/accounts/doctype/tax_withholding_category/test_tax_withholding_category.py

@@ -4,6 +4,7 @@
 import unittest
 
 import frappe
+from frappe.custom.doctype.custom_field.custom_field import create_custom_fields
 from frappe.utils import today
 
 from erpnext.accounts.utils import get_fiscal_year
@@ -17,6 +18,7 @@ class TestTaxWithholdingCategory(unittest.TestCase):
 		# create relevant supplier, etc
 		create_records()
 		create_tax_withholding_category_records()
+		make_pan_no_field()
 
 	def tearDown(self):
 		cancel_invoices()
@@ -451,6 +453,40 @@ class TestTaxWithholdingCategory(unittest.TestCase):
 		pe2.cancel()
 		pe3.cancel()
 
+	def test_lower_deduction_certificate_application(self):
+		frappe.db.set_value(
+			"Supplier",
+			"Test LDC Supplier",
+			{
+				"tax_withholding_category": "Test Service Category",
+				"pan": "ABCTY1234D",
+			},
+		)
+
+		create_lower_deduction_certificate(
+			supplier="Test LDC Supplier",
+			certificate_no="1AE0423AAJ",
+			tax_withholding_category="Test Service Category",
+			tax_rate=2,
+			limit=50000,
+		)
+
+		pi1 = create_purchase_invoice(supplier="Test LDC Supplier", rate=35000)
+		pi1.submit()
+		self.assertEqual(pi1.taxes[0].tax_amount, 700)
+
+		pi2 = create_purchase_invoice(supplier="Test LDC Supplier", rate=35000)
+		pi2.submit()
+		self.assertEqual(pi2.taxes[0].tax_amount, 2300)
+
+		pi3 = create_purchase_invoice(supplier="Test LDC Supplier", rate=35000)
+		pi3.submit()
+		self.assertEqual(pi3.taxes[0].tax_amount, 3500)
+
+		pi1.cancel()
+		pi2.cancel()
+		pi3.cancel()
+
 
 def cancel_invoices():
 	purchase_invoices = frappe.get_all(
@@ -610,6 +646,7 @@ def create_records():
 		"Test TDS Supplier6",
 		"Test TDS Supplier7",
 		"Test TDS Supplier8",
+		"Test LDC Supplier",
 	]:
 		if frappe.db.exists("Supplier", name):
 			continue
@@ -806,3 +843,39 @@ def create_tax_withholding_category(
 				"accounts": [{"company": "_Test Company", "account": account}],
 			}
 		).insert()
+
+
+def create_lower_deduction_certificate(
+	supplier, tax_withholding_category, tax_rate, certificate_no, limit
+):
+	fiscal_year = get_fiscal_year(today(), company="_Test Company")
+	if not frappe.db.exists("Lower Deduction Certificate", certificate_no):
+		frappe.get_doc(
+			{
+				"doctype": "Lower Deduction Certificate",
+				"company": "_Test Company",
+				"supplier": supplier,
+				"certificate_no": certificate_no,
+				"tax_withholding_category": tax_withholding_category,
+				"fiscal_year": fiscal_year[0],
+				"valid_from": fiscal_year[1],
+				"valid_upto": fiscal_year[2],
+				"rate": tax_rate,
+				"certificate_limit": limit,
+			}
+		).insert()
+
+
+def make_pan_no_field():
+	pan_field = {
+		"Supplier": [
+			{
+				"fieldname": "pan",
+				"label": "PAN",
+				"fieldtype": "Data",
+				"translatable": 0,
+			}
+		]
+	}
+
+	create_custom_fields(pan_field, update=1)