diff --git a/core/modules/hal/hal.services.yml b/core/modules/hal/hal.services.yml
index 7b30432..e817fbf 100644
--- a/core/modules/hal/hal.services.yml
+++ b/core/modules/hal/hal.services.yml
@@ -4,11 +4,6 @@ services:
     arguments: ['@rest.link_manager', '@serializer.entity_resolver']
     tags:
       - { name: normalizer, priority: 10 }
-  serializer.normalizer.timestamp_item.hal:
-    class: Drupal\hal\Normalizer\TimestampItemNormalizer
-    arguments: ['@date.formatter', '@config.factory']
-    tags:
-      - { name: normalizer, priority: 10 }
   serializer.normalizer.field_item.hal:
     class: Drupal\hal\Normalizer\FieldItemNormalizer
     tags:
diff --git a/core/modules/hal/src/Normalizer/TimestampItemNormalizer.php b/core/modules/hal/src/Normalizer/TimestampItemNormalizer.php
deleted file mode 100644
index 8263f2c..0000000
--- a/core/modules/hal/src/Normalizer/TimestampItemNormalizer.php
+++ /dev/null
@@ -1,80 +0,0 @@
-<?php
-
-namespace Drupal\hal\Normalizer;
-
-use Drupal\Core\Config\ConfigFactoryInterface;
-use Drupal\Core\Datetime\DateFormatterInterface;
-
-/**
- * Converts values for TimestampItem to and from common formats.
- */
-class TimestampItemNormalizer extends FieldItemNormalizer {
-
-  /**
-   * The date formatter service.
-   *
-   * @var \Drupal\Core\Datetime\DateFormatterInterface
-   */
-  protected $dateFormatter;
-
-  /**
-   * The config factory.
-   *
-   * @var \Drupal\Core\Config\ConfigFactoryInterface
-   */
-  protected $configFactory;
-
-  /**
-   * The interface or class that this Normalizer supports.
-   *
-   * @var string
-   */
-  protected $supportedInterfaceOrClass = 'Drupal\Core\Field\Plugin\Field\FieldType\TimestampItem';
-
-  /**
-   * Constructs an TimestampItemNormalizer object.
-   *
-   * @param \Drupal\Core\Datetime\DateFormatterInterface $date_formatter
-   *   The date formatter service.
-   * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
-   *   The config factory.
-   */
-  public function __construct(DateFormatterInterface $date_formatter, ConfigFactoryInterface $config_factory) {
-    $this->dateFormatter = $date_formatter;
-    $this->configFactory = $config_factory;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function normalize($field_item, $format = NULL, array $context = array()) {
-    /** @var $field_item \Drupal\Core\Field\Plugin\Field\FieldType\TimestampItem */
-    $value = $field_item->getValue()['value'];
-    $field = $field_item->getParent();
-
-    return [
-      $field->getName() => ['value' => $this->dateFormatter->format($value, 'custom', \DateTime::RFC3339, 'UTC')],
-    ];
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  protected function constructValue($data, $context) {
-    $formats = [
-      'U',
-      \DateTime::ISO8601,
-      \DateTime::RFC3339,
-    ];
-    $timezone = new \DateTimeZone('UTC');
-
-    foreach ($formats as $format) {
-      if (($date = \DateTime::createFromFormat($format, $data, $timezone)) !== FALSE) {
-        return ['value' => (int) $date->format('U')];
-      }
-    }
-
-    return NULL;
-  }
-
-}
diff --git a/core/modules/rest/config/install/rest.settings.yml b/core/modules/rest/config/install/rest.settings.yml
index 0d9e088..eb3da2d 100644
--- a/core/modules/rest/config/install/rest.settings.yml
+++ b/core/modules/rest/config/install/rest.settings.yml
@@ -9,11 +9,3 @@ link_domain: ~
 # @see rest_update_8203()
 # @see https://www.drupal.org/node/2664780
 bc_entity_resource_permissions: false
-
-# Before Drupal 8.3, timestamps were always returned as Unix timestamps, which
-# are not a universal format for interchance. Instead, RFC3339 timestamps are
-# returned. New Drupal installations opt out from this by default (hence this
-# is set to false), existing installations opt in to it.
-# @see rest_update_8301()
-# @see https://www.drupal.org/node/2768651
-bc_timestamp_normalizer: false
diff --git a/core/modules/rest/config/schema/rest.schema.yml b/core/modules/rest/config/schema/rest.schema.yml
index 7410992..2c255ab 100644
--- a/core/modules/rest/config/schema/rest.schema.yml
+++ b/core/modules/rest/config/schema/rest.schema.yml
@@ -9,9 +9,6 @@ rest.settings:
     bc_entity_resource_permissions:
       type: boolean
       label: 'Whether the pre Drupal 8.2.x behavior of having permissions for EntityResource is enabled or not.'
-    bc_timestamp_normalizer:
-      type: boolean
-      label: 'Whether the pre Drupal 8.3.x behavior of returning Unix timestamps is enabled or not.'
 
 # Method-level granularity of REST resource configuration.
 rest_resource.method:
diff --git a/core/modules/rest/rest.install b/core/modules/rest/rest.install
index f5bb99b..af6664e 100644
--- a/core/modules/rest/rest.install
+++ b/core/modules/rest/rest.install
@@ -94,23 +94,3 @@ function rest_update_8203() {
 /**
  * @} End of "defgroup updates-8.1.x-to-8.2.x".
  */
-
-/**
- * @defgroup updates-8.2.x-to-8.3.x
- * @{
- * Update functions from 8.2.x to 8.3.x.
- */
-
-/**
- * Enable BC for Timestamp: return Unix timestamps.
- */
-function rest_update_8301() {
-  $config_factory = \Drupal::configFactory();
-  $rest_settings = $config_factory->getEditable('rest.settings');
-  $rest_settings->set('bc_timestamp_normalizer', TRUE)
-    ->save(TRUE);
-}
-
-/**
- * @} End of "defgroup updates-8.2.x-to-8.3.x".
- */
diff --git a/core/modules/serialization/config/install/serialization.settings.yml b/core/modules/serialization/config/install/serialization.settings.yml
new file mode 100644
index 0000000..3d846ed
--- /dev/null
+++ b/core/modules/serialization/config/install/serialization.settings.yml
@@ -0,0 +1,7 @@
+# Before Drupal 8.3, timestamps were always returned as Unix timestamps, which
+# are not a universal format for interchange. Instead, RFC3339 timestamps are
+# returned. New Drupal installations opt out from this by default (hence this
+# is set to false), existing installations opt in to it.
+# @see rest_update_8301()
+# @see https://www.drupal.org/node/2768651
+bc_timestamp_normalizer_unix: false
diff --git a/core/modules/serialization/config/schema/serialization.schema.yml b/core/modules/serialization/config/schema/serialization.schema.yml
new file mode 100644
index 0000000..770e7b7
--- /dev/null
+++ b/core/modules/serialization/config/schema/serialization.schema.yml
@@ -0,0 +1,8 @@
+# Schema for the configuration files of the Serialization module.
+serialization.settings:
+  type: config_object
+  label: 'Serialization settings'
+  mapping:
+    bc_timestamp_normalizer_unix:
+      type: boolean
+      label: 'Whether the pre Drupal 8.3.x behavior of returning Unix timestamps is enabled or not.'
diff --git a/core/modules/serialization/serialization.install b/core/modules/serialization/serialization.install
new file mode 100644
index 0000000..b78e716
--- /dev/null
+++ b/core/modules/serialization/serialization.install
@@ -0,0 +1,26 @@
+<?php
+
+/**
+ * @file
+ * Install, update and uninstall functions for the serialization module.
+ */
+
+/**
+ * @defgroup updates-8.2.x-to-8.3.x
+ * @{
+ * Update functions from 8.2.x to 8.3.x.
+ */
+
+/**
+ * Enable BC for Timestamp: return Unix timestamps.
+ */
+function serialization_update_8301() {
+  $config_factory = \Drupal::configFactory();
+  $rest_settings = $config_factory->getEditable('serialization.settings');
+  $rest_settings->set('bc_timestamp_normalizer_unix', TRUE)
+    ->save(TRUE);
+}
+
+/**
+* @} End of "defgroup updates-8.2.x-to-8.3.x".
+*/
diff --git a/core/modules/serialization/serialization.services.yml b/core/modules/serialization/serialization.services.yml
index 8b570c0..6759ad1 100644
--- a/core/modules/serialization/serialization.services.yml
+++ b/core/modules/serialization/serialization.services.yml
@@ -45,6 +45,11 @@ services:
     class: Drupal\serialization\Normalizer\TypedDataNormalizer
     tags:
       - { name: normalizer }
+  serializer.normalizer.timestamp_item:
+    class: Drupal\serialization\Normalizer\TimestampItemNormalizer
+    arguments: ['@date.formatter', '@config.factory']
+    tags:
+      - { name: normalizer }
   serializer.encoder.json:
     class: Drupal\serialization\Encoder\JsonEncoder
     tags:
diff --git a/core/modules/serialization/src/Normalizer/TimestampItemNormalizer.php b/core/modules/serialization/src/Normalizer/TimestampItemNormalizer.php
new file mode 100644
index 0000000..2da243b
--- /dev/null
+++ b/core/modules/serialization/src/Normalizer/TimestampItemNormalizer.php
@@ -0,0 +1,113 @@
+<?php
+
+namespace Drupal\serialization\Normalizer;
+
+use Drupal\Core\Config\ConfigFactoryInterface;
+use Drupal\Core\Datetime\DateFormatterInterface;
+use Drupal\Core\TypedData\DataDefinition;
+use Drupal\Core\Field\Plugin\Field\FieldType\TimestampItem;
+use Symfony\Component\Serializer\Exception\UnexpectedValueException;
+use Symfony\Component\Serializer\Normalizer\DenormalizerInterface;
+
+/**
+ * Converts values for TimestampItem to and from common formats.
+ */
+class TimestampItemNormalizer extends NormalizerBase implements DenormalizerInterface {
+
+  /**
+   * The date formatter service.
+   *
+   * @var \Drupal\Core\Datetime\DateFormatterInterface
+   */
+  protected $dateFormatter;
+
+  /**
+   * The config factory.
+   *
+   * @var \Drupal\Core\Config\ConfigFactoryInterface
+   */
+  protected $configFactory;
+
+  /**
+   * The interface or class that this Normalizer supports.
+   *
+   * @var string
+   */
+  protected $supportedInterfaceOrClass = TimestampItem::class;
+
+  /**
+   * Allowed timestamps formats for the denormalizer.
+   *
+   * The denormalizer allows deserialization to timestamps from several
+   * different formats. Validation of the input data and creation of the
+   * numerical timestamp value is handled with \DateTime::createFromFormat().
+   * The list is chosen to be unambiguous and language neutral, but also common
+   * for data interchange.
+   * @see http://php.net/manual/en/datetime.createfromformat.php
+   *
+   * @var string[]
+   */
+  protected $allowedFormats = [
+    'U',
+    \DateTime::ISO8601,
+    \DateTime::RFC3339,
+  ];
+
+  /**
+   * Constructs an TimestampItemNormalizer object.
+   *
+   * @param \Drupal\Core\Datetime\DateFormatterInterface $date_formatter
+   *   The date formatter service.
+   * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
+   *   The config factory.
+   */
+  public function __construct(DateFormatterInterface $date_formatter, ConfigFactoryInterface $config_factory) {
+    $this->dateFormatter = $date_formatter;
+    $this->configFactory = $config_factory;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function normalize($field_item, $format = NULL, array $context = array()) {
+    /** @var $field_item \Drupal\Core\Field\Plugin\Field\FieldType\TimestampItem */
+    $value = $field_item->getValue()['value'];
+    $field = $field_item->getParent();
+
+    // Check for the BC setting. If TRUE, use a Unix timestamp. Otherwise, use
+    // a RFC 3339 timestamp with the time zone set to UTC.
+    if ($this->configFactory->get('serialization.settings')->get('bc_timestamp_normalizer_unix')) {
+      $format = 'U';
+    }
+    else {
+      $format = \DateTime::RFC3339;
+    }
+
+    return [
+      $field->getName() => ['value' => $this->dateFormatter->format($value, 'custom', $format, 'UTC')],
+    ];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function denormalize($data, $class, $format = NULL, array $context = []) {
+    // Loop through the allowed formats and create a TimestampItem from the
+    // input data if it matches the defined pattern. Since the formats are
+    // unambiguous (i.e., they reference an absolute time with a defined time
+    // zone), only one will ever match.
+
+    $timezone = new \DateTimeZone('UTC');
+    foreach ($this->allowedFormats as $format) {
+      if (($date = \DateTime::createFromFormat($format, $data, $timezone)) !== FALSE) {
+        $data_definition = DataDefinition::create('timestamp');
+        $timestamp_item = TimestampItem::createInstance($data_definition)
+          ->setValue(['value' => (int) $date->format('U')]);
+        return $timestamp_item;
+      }
+    }
+
+    throw new UnexpectedValueException(sprintf('The specified date "%s" is not in an accepted format.', $data));
+  }
+
+}