diff --git a/Doc/library/tempfile.rst b/Doc/library/tempfile.rst
index bf9198e175a0e1..8a00701e37137b 100644
--- a/Doc/library/tempfile.rst
+++ b/Doc/library/tempfile.rst
@@ -172,6 +172,9 @@ The module defines the following user-callable items:
       :class:`io.TextIOBase` abstract base classes (depending on whether binary
       or text *mode* was specified).
 
+   .. versionchanged:: next
+      The truncate method returns new file size.
+
 
 .. class:: TemporaryDirectory(suffix=None, prefix=None, dir=None, ignore_cleanup_errors=False, *, delete=True)
 
@@ -391,8 +394,10 @@ Here are some examples of typical usage of the :mod:`!tempfile` module::
     # create a temporary file and write some data to it
     >>> fp = tempfile.TemporaryFile()
     >>> fp.write(b'Hello world!')
+    12
     # read data from file
     >>> fp.seek(0)
+    0
     >>> fp.read()
     b'Hello world!'
     # close the file, it will be removed
@@ -403,6 +408,8 @@ Here are some examples of typical usage of the :mod:`!tempfile` module::
     ...     fp.write(b'Hello world!')
     ...     fp.seek(0)
     ...     fp.read()
+    12
+    0
     b'Hello world!'
     >>>
     # file is now closed and removed
diff --git a/Lib/test/test_tempfile.py b/Lib/test/test_tempfile.py
index b2b5390af33b00..c5d5e4aa572e59 100644
--- a/Lib/test/test_tempfile.py
+++ b/Lib/test/test_tempfile.py
@@ -1532,6 +1532,19 @@ def test_truncate_with_size_parameter(self):
         self.assertTrue(f._rolled)
         self.assertEqual(os.fstat(f.fileno()).st_size, 20)
 
+    def test_truncate_return_size(self):
+        "SpooledTemporaryFile truncate should return new position"
+        f = tempfile.SpooledTemporaryFile(max_size=10)
+        f.write(b'abcdef')
+        self.assertEqual(f.truncate(3), 3)
+
+    def test_seek_return_position(self):
+        "SpooledTemporaryFile seek should return file position"
+        f = tempfile.SpooledTemporaryFile(max_size=10)
+        f.write(b'abcdef')
+        self.assertEqual(f.seek(3), 3)
+        self.assertEqual(f.seek(0, 2), 6)
+
     def test_class_getitem(self):
         self.assertIsInstance(tempfile.SpooledTemporaryFile[bytes],
                       types.GenericAlias)
diff --git a/Misc/NEWS.d/next/Library/2021-10-24-01-28-07.bpo-45593.QjC6-D.rst b/Misc/NEWS.d/next/Library/2021-10-24-01-28-07.bpo-45593.QjC6-D.rst
new file mode 100644
index 00000000000000..8609b15cc78a13
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2021-10-24-01-28-07.bpo-45593.QjC6-D.rst
@@ -0,0 +1 @@
+Make :meth:`!tempfile.SpooledTemporaryFile.truncate` return new file size.