diff --git a/pandas/_libs/tslibs/dtypes.pyx b/pandas/_libs/tslibs/dtypes.pyx
index 7e6e382c17cc6..4100f3d90e817 100644
--- a/pandas/_libs/tslibs/dtypes.pyx
+++ b/pandas/_libs/tslibs/dtypes.pyx
@@ -359,6 +359,8 @@ cdef dict c_PERIOD_AND_OFFSET_DEPR_FREQSTR = {
     "b": "B",
     "c": "C",
     "MIN": "min",
+    "US": "us",
+    "NS": "ns",
 }
 
 cdef str INVALID_FREQ_ERR_MSG = "Invalid frequency: {0}"
diff --git a/pandas/_libs/tslibs/offsets.pyx b/pandas/_libs/tslibs/offsets.pyx
index db35cc0c93237..5b913a3ccdea1 100644
--- a/pandas/_libs/tslibs/offsets.pyx
+++ b/pandas/_libs/tslibs/offsets.pyx
@@ -4695,15 +4695,16 @@ _lite_rule_alias = {
     "YS": "YS-JAN",    # YearBegin(month=1),
     "BYE": "BYE-DEC",    # BYearEnd(month=12),
     "BYS": "BYS-JAN",  # BYearBegin(month=1),
-
-    "Min": "min",
-    "min": "min",
-    "ms": "ms",
-    "us": "us",
-    "ns": "ns",
 }
 
-_dont_uppercase = {"h", "bh", "cbh", "MS", "ms", "s"}
+_dont_uppercase = {
+    "h",
+    "bh",
+    "cbh",
+    "MS",
+    "ms",
+    "s",
+}
 
 
 INVALID_FREQ_ERR_MSG = "Invalid frequency: {0}"
diff --git a/pandas/tests/arrays/test_datetimes.py b/pandas/tests/arrays/test_datetimes.py
index de189b7e2f724..1e67acc22c486 100644
--- a/pandas/tests/arrays/test_datetimes.py
+++ b/pandas/tests/arrays/test_datetimes.py
@@ -760,7 +760,7 @@ def test_date_range_frequency_M_Q_Y_raises(self, freq):
         with pytest.raises(ValueError, match=msg):
             pd.date_range("1/1/2000", periods=4, freq=freq)
 
-    @pytest.mark.parametrize("freq_depr", ["2MIN", "2mS", "2Us"])
+    @pytest.mark.parametrize("freq_depr", ["2MIN", "2NS", "2US"])
     def test_date_range_uppercase_frequency_deprecated(self, freq_depr):
         # GH#9586, GH#54939
         depr_msg = f"'{freq_depr[1:]}' is deprecated and will be removed in a "
diff --git a/pandas/tests/tslibs/test_to_offset.py b/pandas/tests/tslibs/test_to_offset.py
index 67521c7e2a3ac..569c7af3045df 100644
--- a/pandas/tests/tslibs/test_to_offset.py
+++ b/pandas/tests/tslibs/test_to_offset.py
@@ -204,7 +204,7 @@ def test_to_offset_lowercase_frequency_raises(freq_depr):
         to_offset(freq_depr)
 
 
-@pytest.mark.parametrize("freq_depr", ["2MIN", "2Us", "2NS"])
+@pytest.mark.parametrize("freq_depr", ["2MIN", "2US", "2NS"])
 def test_to_offset_uppercase_frequency_deprecated(freq_depr):
     # GH#54939
     depr_msg = f"'{freq_depr[1:]}' is deprecated and will be removed in a "