diff --git a/erpnext/stock/report/delayed_item_report/test_delayed_item_report.py b/erpnext/stock/report/delayed_item_report/test_delayed_item_report.py
new file mode 100644
index 00000000000..39a8d740803
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+++ b/erpnext/stock/report/delayed_item_report/test_delayed_item_report.py
@@ -0,0 +1,68 @@
+# Copyright (c) 2026, Frappe Technologies Pvt. Ltd. and Contributors
+# See license.txt
+
+import frappe
+
+from erpnext.selling.doctype.sales_order.mapper import make_delivery_note
+from erpnext.selling.doctype.sales_order.test_sales_order import make_sales_order
+from erpnext.stock.doctype.stock_entry.stock_entry_utils import make_stock_entry
+from erpnext.stock.report.delayed_item_report.delayed_item_report import execute
+from erpnext.tests.utils import ERPNextTestSuite
+
+
+class TestDelayedItemReport(ERPNextTestSuite):
+	def run_report(self, **extra):
+		filters = frappe._dict(
+			{
+				"company": "_Test Company",
+				"based_on": "Delivery Note",
+				"from_date": "2026-06-01",
+				"to_date": "2026-06-30",
+			}
+		)
+		filters.update(extra)
+		return execute(filters)[1]
+
+	def test_late_delivery_shows_delay(self):
+		item = "_Test Item"
+
+		make_stock_entry(
+			item_code=item,
+			qty=10,
+			to_warehouse="Stores - _TC",
+			rate=100,
+			posting_date="2026-06-01",
+			company="_Test Company",
+		)
+
+		so = make_sales_order(
+			item_code=item,
+			qty=10,
+			rate=100,
+			warehouse="Stores - _TC",
+			transaction_date="2026-06-01",
+			company="_Test Company",
+			do_not_submit=True,
+		)
+		so.delivery_date = "2026-06-05"
+		for row in so.items:
+			row.delivery_date = "2026-06-05"
+		so.submit()
+
+		dn = make_delivery_note(so.name)
+		dn.posting_date = "2026-06-10"
+		dn.set_posting_time = 1
+		dn.insert()
+		dn.submit()
+
+		rows = self.run_report(sales_order=so.name)
+
+		matching = [r for r in rows if r.get("name") == dn.name and r.get("item_code") == item]
+		self.assertTrue(matching, f"No report row found for DN {dn.name} / item {item}")
+
+		row = matching[0]
+		self.assertEqual(row.get("sales_order"), so.name)
+		self.assertEqual(str(row.get("delivery_date")), "2026-06-05")
+		self.assertEqual(str(row.get("posting_date")), "2026-06-10")
+		# delayed_days = date_diff(actual posting_date, expected delivery_date)
+		self.assertEqual(row.get("delayed_days"), 5)