diff --git a/erpnext/projects/report/timesheet_billing_summary/test_timesheet_billing_summary.py b/erpnext/projects/report/timesheet_billing_summary/test_timesheet_billing_summary.py
new file mode 100644
index 00000000000..5526d5db01c
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+++ b/erpnext/projects/report/timesheet_billing_summary/test_timesheet_billing_summary.py
@@ -0,0 +1,62 @@
+# Copyright (c) 2026, Frappe Technologies Pvt. Ltd. and Contributors
+# See license.txt
+
+import frappe
+
+from erpnext.projects.doctype.timesheet.test_timesheet import make_timesheet
+from erpnext.projects.report.timesheet_billing_summary.timesheet_billing_summary import execute
+from erpnext.setup.doctype.employee.test_employee import make_employee
+from erpnext.tests.utils import ERPNextTestSuite
+
+
+class TestTimesheetBillingSummary(ERPNextTestSuite):
+	"""Lists submitted Timesheet Detail rows with working/billing hours and amount,
+	optionally grouped by date/project/employee."""
+
+	def setUp(self):
+		self.employee = make_employee("timesheet_billing@example.com", company="_Test Company")
+		self.project = frappe.get_doc(
+			{
+				"doctype": "Project",
+				"project_name": f"_Test TBS {frappe.generate_hash(length=6)}",
+				"company": "_Test Company",
+			}
+		).insert()
+
+	def make_ts(self, is_billable=1):
+		return make_timesheet(
+			self.employee, simulate=True, is_billable=is_billable, project=self.project.name
+		)
+
+	def run_report(self, **extra):
+		filters = frappe._dict({"company": "_Test Company", "employee": self.employee})
+		filters.update(extra)
+		return execute(filters)[1]
+
+	def test_billable_timesheet_row(self):
+		ts = self.make_ts(is_billable=1)
+		detail = ts.time_logs[0]
+
+		rows = [r for r in self.run_report() if r.get("timesheet") == ts.name]
+		self.assertTrue(rows, "Timesheet missing from report")
+		row = rows[0]
+		self.assertEqual(row["hours"], 2)
+		self.assertEqual(row["billing_hours"], detail.billing_hours)
+		self.assertEqual(row["billing_amount"], detail.billing_amount)
+		self.assertEqual(row["project"], self.project.name)
+
+	def test_group_by_project_sums_hours(self):
+		self.make_ts(is_billable=1)
+
+		data = self.run_report(group_by="project")
+		group_rows = [r for r in data if r.get("is_group") and r.get("project") == self.project.name]
+		self.assertTrue(group_rows, "Grouped project row missing")
+		self.assertEqual(group_rows[0]["hours"], 2)
+
+	def test_draft_excluded_unless_requested(self):
+		ts = make_timesheet(self.employee, is_billable=1, project=self.project.name, do_not_submit=True)
+
+		# submitted-only by default: the draft timesheet is absent
+		self.assertNotIn(ts.name, {r.get("timesheet") for r in self.run_report()})
+		# ... but included when draft timesheets are requested
+		self.assertIn(ts.name, {r.get("timesheet") for r in self.run_report(include_draft_timesheets=1)})