diff --git a/tests/test_reconcile.py b/tests/test_reconcile.py
index 292de3648d6476d04415aba9ffc7300da6fe9dc9..ba6d6ac655118e61351e7ca7e679fc6afed46f9d 100644
--- a/tests/test_reconcile.py
+++ b/tests/test_reconcile.py
@@ -5,6 +5,8 @@ import os
 import tempfile
 import textwrap
 
+import pytest
+
 from conservancy_beancount.reconcile.statement_reconciler import (
     date_proximity,
     format_output,
@@ -15,6 +17,7 @@ from conservancy_beancount.reconcile.statement_reconciler import (
     read_fr_csv,
     remove_duplicate_words,
     remove_payee_junk,
+    round_to_month,
     subset_match,
     totals,
     write_metadata_to_books,
@@ -388,3 +391,20 @@ def test_format_output():
     matches, _, _ = match_statement_and_books(statement, books)
     output = format_output(matches, datetime.date(2022, 1, 1), datetime.date(2022, 2, 1), 'test.csv', True)
     assert '2022-01-01:       10.00 Patreon         / Patreon   / 12345  →  2022-01-01:       10.00 Patreon                              ✓ Matched' in output
+
+
+month_test_data = [
+    ((datetime.date(2022, 1, 2), datetime.date(2022, 1, 30)),
+     (datetime.date(2022, 1, 1), datetime.date(2022, 1, 31))),
+    ((datetime.date(2022, 4, 2), datetime.date(2022, 4, 29)),
+     (datetime.date(2022, 4, 1), datetime.date(2022, 4, 30))),
+    ((datetime.date(2022, 2, 2), datetime.date(2022, 2, 27)),
+     (datetime.date(2022, 2, 1), datetime.date(2022, 2, 28))),
+    ((datetime.date(2024, 2, 2), datetime.date(2024, 2, 27)),
+     (datetime.date(2024, 2, 1), datetime.date(2024, 2, 29))),
+]
+
+
+@pytest.mark.parametrize('input_dates,rounded_dates', month_test_data)
+def test_rounds_to_full_month(input_dates, rounded_dates):
+    assert round_to_month(*input_dates) == rounded_dates