BUG: Timestamp(pd.NA) raising TypeError

doc/source/whatsnew/v2.1.0.rst

@@ -435,6 +435,7 @@ Datetimelike
 - Bug in :meth:`arrays.DatetimeArray.map` and :meth:`DatetimeIndex.map`, where the supplied callable operated array-wise instead of element-wise (:issue:`51977`)
 - Bug in constructing a :class:`Series` or :class:`DataFrame` from a datetime or timedelta scalar always inferring nanosecond resolution instead of inferring from the input (:issue:`52212`)
 - Bug in constructing a :class:`Timestamp` from a string representing a time without a date inferring an incorrect unit (:issue:`54097`)
+- Bug in constructing a :class:`Timestamp` with ``ts_input=pd.NA`` raising ``TypeError`` (:issue:`45481`)
 - Bug in parsing datetime strings with weekday but no day e.g. "2023 Sept Thu" incorrectly raising ``AttributeError`` instead of ``ValueError`` (:issue:`52659`)
 
 Timedelta

pandas/_libs/tslibs/conversion.pyx

@@ -25,6 +25,7 @@ from cpython.datetime cimport (
 
 import_datetime()
 
+from pandas._libs.missing cimport checknull_with_nat_and_na
 from pandas._libs.tslibs.base cimport ABCTimestamp
 from pandas._libs.tslibs.dtypes cimport (
     abbrev_to_npy_unit,
@@ -57,7 +58,6 @@ from pandas._libs.tslibs.np_datetime import OutOfBoundsDatetime
 
 from pandas._libs.tslibs.nattype cimport (
     NPY_NAT,
-    c_NaT as NaT,
     c_nat_strings as nat_strings,
 )
 from pandas._libs.tslibs.parsing cimport parse_datetime_string
@@ -268,7 +268,7 @@ cdef _TSObject convert_to_tsobject(object ts, tzinfo tz, str unit,
     if isinstance(ts, str):
         return convert_str_to_tsobject(ts, tz, unit, dayfirst, yearfirst)
 
-    if ts is None or ts is NaT:
+    if checknull_with_nat_and_na(ts):
         obj.value = NPY_NAT
     elif is_datetime64_object(ts):
         reso = get_supported_reso(get_datetime64_unit(ts))

pandas/tests/scalar/timestamp/test_constructors.py

@@ -18,6 +18,8 @@
 from pandas.errors import OutOfBoundsDatetime
 
 from pandas import (
+    NA,
+    NaT,
     Period,
     Timedelta,
     Timestamp,
@@ -898,3 +900,11 @@ def test_timestamp_constructor_adjust_value_for_fold(tz, ts_input, fold, value_o
     result = ts._value
     expected = value_out
     assert result == expected
+
+
+@pytest.mark.parametrize("na_value", [None, np.nan, np.datetime64("NaT"), NaT, NA])
+def test_timestamp_constructor_na_value(na_value):
+    # GH45481
+    result = Timestamp(na_value)
+    expected = NaT
+    assert result is expected