diff --git a/Doc/deprecations/index.rst b/Doc/deprecations/index.rst
index f3cecb321d6..c91c64a1092 100644
--- a/Doc/deprecations/index.rst
+++ b/Doc/deprecations/index.rst
@@ -7,6 +7,8 @@ Deprecations
 
 .. include:: pending-removal-in-3.17.rst
 
+.. include:: pending-removal-in-3.18.rst
+
 .. include:: pending-removal-in-3.19.rst
 
 .. include:: pending-removal-in-3.20.rst
diff --git a/Doc/deprecations/pending-removal-in-3.18.rst b/Doc/deprecations/pending-removal-in-3.18.rst
new file mode 100644
index 00000000000..3e799219478
--- /dev/null
+++ b/Doc/deprecations/pending-removal-in-3.18.rst
@@ -0,0 +1,9 @@
+Pending removal in Python 3.18
+------------------------------
+
+* :mod:`decimal`:
+
+  * The non-standard and undocumented :class:`~decimal.Decimal` format
+    specifier ``'N'``, which is only supported in the :mod:`!decimal` module's
+    C implementation, has been deprecated since Python 3.13.
+    (Contributed by Serhiy Storchaka in :gh:`89902`.)
diff --git a/Doc/whatsnew/3.13.rst b/Doc/whatsnew/3.13.rst
index dc105156f33..3be6dcb3eac 100644
--- a/Doc/whatsnew/3.13.rst
+++ b/Doc/whatsnew/3.13.rst
@@ -1861,6 +1861,7 @@ New Deprecations
   * Deprecate the non-standard and undocumented :class:`~decimal.Decimal`
     format specifier ``'N'``,
     which is only supported in the :mod:`!decimal` module's C implementation.
+    Scheduled to be removed in Python 3.18.
     (Contributed by Serhiy Storchaka in :gh:`89902`.)
 
 * :mod:`dis`:
@@ -2024,6 +2025,8 @@ New Deprecations
 
 .. include:: ../deprecations/pending-removal-in-3.17.rst
 
+.. include:: ../deprecations/pending-removal-in-3.18.rst
+
 .. include:: ../deprecations/pending-removal-in-3.19.rst
 
 .. include:: ../deprecations/pending-removal-in-3.20.rst
diff --git a/Doc/whatsnew/3.14.rst b/Doc/whatsnew/3.14.rst
index c12a1920b10..d4517183d69 100644
--- a/Doc/whatsnew/3.14.rst
+++ b/Doc/whatsnew/3.14.rst
@@ -2718,6 +2718,8 @@ New deprecations
 
 .. include:: ../deprecations/pending-removal-in-3.17.rst
 
+.. include:: ../deprecations/pending-removal-in-3.18.rst
+
 .. include:: ../deprecations/pending-removal-in-3.19.rst
 
 .. include:: ../deprecations/pending-removal-in-3.20.rst
diff --git a/Doc/whatsnew/3.15.rst b/Doc/whatsnew/3.15.rst
index 39d6fb6572c..17415f888b6 100644
--- a/Doc/whatsnew/3.15.rst
+++ b/Doc/whatsnew/3.15.rst
@@ -1171,6 +1171,8 @@ New deprecations
 
 .. include:: ../deprecations/pending-removal-in-3.17.rst
 
+.. include:: ../deprecations/pending-removal-in-3.18.rst
+
 .. include:: ../deprecations/pending-removal-in-3.19.rst
 
 .. include:: ../deprecations/pending-removal-in-3.20.rst
diff --git a/Modules/_decimal/_decimal.c b/Modules/_decimal/_decimal.c
index e183c70653b..33e624e342e 100644
--- a/Modules/_decimal/_decimal.c
+++ b/Modules/_decimal/_decimal.c
@@ -3764,7 +3764,8 @@ _decimal_Decimal___format___impl(PyObject *dec, PyTypeObject *cls,
 
     if (size > 0 && fmt[size-1] == 'N') {
         if (PyErr_WarnEx(PyExc_DeprecationWarning,
-                         "Format specifier 'N' is deprecated", 1) < 0) {
+                         "Format specifier 'N' is deprecated and "
+                         "slated for removal in Python 3.18", 1) < 0) {
             return NULL;
         }
     }