diff --git a/erpnext/accounts/doctype/journal_entry_template/journal_entry_template.py b/erpnext/accounts/doctype/journal_entry_template/journal_entry_template.py
index f86706774fc..e552ee1ca20 100644
--- a/erpnext/accounts/doctype/journal_entry_template/journal_entry_template.py
+++ b/erpnext/accounts/doctype/journal_entry_template/journal_entry_template.py
@@ -45,6 +45,20 @@ class JournalEntryTemplate(Document):
 
 	def validate(self):
 		self.validate_party()
+		self.validate_account_company()
+
+	def validate_account_company(self):
+		"""Each row's account must belong to the template's company."""
+		for account in self.accounts:
+			if (
+				account.account
+				and frappe.get_cached_value("Account", account.account, "company") != self.company
+			):
+				frappe.throw(
+					_("Row {0}: Account {1} does not belong to company {2}").format(
+						account.idx, account.account, self.company
+					)
+				)
 
 	def validate_party(self):
 		"""
diff --git a/erpnext/accounts/doctype/journal_entry_template/test_journal_entry_template.py b/erpnext/accounts/doctype/journal_entry_template/test_journal_entry_template.py
index 616327e8493..8b6bed1bca0 100644
--- a/erpnext/accounts/doctype/journal_entry_template/test_journal_entry_template.py
+++ b/erpnext/accounts/doctype/journal_entry_template/test_journal_entry_template.py
@@ -1,9 +1,45 @@
-# Copyright (c) 2020, Frappe Technologies Pvt. Ltd. and Contributors
+# Copyright (c) 2026, Frappe Technologies Pvt. Ltd. and Contributors
 # See license.txt
-# import frappe
+
+import frappe
 
 from erpnext.tests.utils import ERPNextTestSuite
 
+COMPANY = "_Test Company"
+
 
 class TestJournalEntryTemplate(ERPNextTestSuite):
-	pass
+	"""Journal Entry Template's only real rule is validate_party: party_type is
+	allowed only on Receivable/Payable accounts, and a party needs a party_type."""
+
+	def setUp(self):
+		frappe.set_user("Administrator")
+
+	def make_template(self, rows, company=COMPANY):
+		doc = frappe.new_doc("Journal Entry Template")
+		doc.template_title = f"_Test JET {frappe.generate_hash(length=6)}"
+		doc.company = company
+		doc.voucher_type = "Journal Entry"
+		doc.naming_series = frappe.get_meta("Journal Entry").get_field("naming_series").options.split("\n")[0]
+		for row in rows:
+			doc.append("accounts", row)
+		return doc
+
+	def test_party_type_only_on_receivable_or_payable_account(self):
+		# Cash is neither Receivable nor Payable, so a party_type here is invalid
+		doc = self.make_template([{"account": "Cash - _TC", "party_type": "Customer"}])
+		self.assertRaises(frappe.ValidationError, doc.validate)
+
+	def test_party_requires_party_type(self):
+		doc = self.make_template([{"account": "Debtors - _TC", "party": "_Test Customer"}])
+		self.assertRaises(frappe.ValidationError, doc.validate)
+
+	def test_account_from_other_company_is_rejected(self):
+		other_receivable = frappe.db.get_value(
+			"Account", {"company": "_Test Company 1", "account_type": "Receivable", "is_group": 0}, "name"
+		)
+		self.assertTrue(other_receivable, "need a receivable account in _Test Company 1")
+		doc = self.make_template(
+			[{"account": other_receivable, "party_type": "Customer", "party": "_Test Customer"}]
+		)
+		self.assertRaises(frappe.ValidationError, doc.insert)