diff --git a/tests/test_plugin_txn_date.py b/tests/test_plugin_txn_date.py
new file mode 100644
index 0000000000000000000000000000000000000000..8c1c056457cf77d675e5f775942db1d64e6b47f5
--- /dev/null
+++ b/tests/test_plugin_txn_date.py
@@ -0,0 +1,79 @@
+"""test_txn_date.py - Unit tests for transaction date validation"""
+# Copyright © 2020  Brett Smith
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+from datetime import date
+
+import pytest
+
+from . import testutil
+
+from conservancy_beancount import config as configmod
+from conservancy_beancount import errors as errormod
+from conservancy_beancount.plugin import txn_date as hookmod
+
+BOOKS_PATH = testutil.test_path('books')
+CONFIG = testutil.TestConfig(books_path=BOOKS_PATH)
+HOOK = hookmod.TransactionDate(CONFIG)
+
+@pytest.mark.parametrize('txn_date,fyear', [
+    (date(2016, 1, 1), 2015),
+    (date(2016, 2, 29), 2015),
+    (date(2016, 3, 1), 2016),
+    (date(2016, 12, 31), 2016),
+    (date(2017, 2, 28), 2016),
+    (date(2017, 3, 1), 2017),
+])
+def test_good_txn(txn_date, fyear):
+    filename = str(BOOKS_PATH / f'{fyear}.beancount')
+    txn = testutil.Transaction(date=txn_date, filename=filename, postings=[
+        ('Assets:Cash', 5),
+        ('Income:Donations', -5),
+    ])
+    assert not list(HOOK.run(txn))
+
+@pytest.mark.parametrize('txn_date,fyear', [
+    (date(2018, 1, 1), 2017),
+    (date(2018, 12, 31), 2018),
+    (date(2019, 3, 1), 2019),
+])
+def test_bad_txn(txn_date, fyear):
+    filename = str(BOOKS_PATH / '2020.beancount')
+    txn = testutil.Transaction(date=txn_date, filename=filename, postings=[
+        ('Assets:Cash', 5),
+        ('Income:Donations', -5),
+    ])
+    errors = list(HOOK.run(txn))
+    assert len(errors) == 1
+    assert errors[0].message == f"transaction dated in FY{fyear} entered in FY2020 books"
+
+@pytest.mark.parametrize('path_s', [
+    'books/2020.beancount',
+    'historical/2020.beancount',
+    'definitions.beancount',
+])
+def test_outer_transactions_not_checked(path_s):
+    txn_date = date(1900, 6, 15)
+    filename = str(BOOKS_PATH / path_s)
+    txn = testutil.Transaction(date=txn_date, filename=filename, postings=[
+        ('Assets:Cash', 5),
+        ('Income:Donations', -5),
+    ])
+    assert not list(HOOK.run(txn))
+
+def test_error_without_books_path():
+    config = configmod.Config()
+    with pytest.raises(errormod.ConfigurationError):
+        hookmod.TransactionDate(config)