diff -u b/core/modules/field/tests/src/Kernel/Migrate/d6/MigrateFieldTest.php b/core/modules/field/tests/src/Kernel/Migrate/d6/MigrateFieldTest.php
--- b/core/modules/field/tests/src/Kernel/Migrate/d6/MigrateFieldTest.php
+++ b/core/modules/field/tests/src/Kernel/Migrate/d6/MigrateFieldTest.php
@@ -68,6 +68,7 @@
     $field_storage = FieldStorageConfig::load('node.field_test_datestamp');
     $this->assertSame("datetime", $field_storage->getType(), t('Field type is @fieldtype. It should be datetime.', array('@fieldtype' => $field_storage->getType())));
     $field_storage = FieldStorageConfig::load('node.field_test_date');
+    $this->assertSame("datetime", $field_storage->getType(), t('Field type is @fieldtype. It should be datetime.', array('@fieldtype' => $field_storage->getType())));
 
     // Decimal field with radio buttons.
     $field_storage = FieldStorageConfig::load('node.field_test_decimal_radio_buttons');
diff -u b/core/modules/node/tests/src/Kernel/Migrate/d6/MigrateNodeTest.php b/core/modules/node/tests/src/Kernel/Migrate/d6/MigrateNodeTest.php
--- b/core/modules/node/tests/src/Kernel/Migrate/d6/MigrateNodeTest.php
+++ b/core/modules/node/tests/src/Kernel/Migrate/d6/MigrateNodeTest.php
@@ -73,8 +73,8 @@
     $this->assertIdentical('This is a field with exclude unset.', $node->field_test_exclude_unset->value, 'Field with exclude unset is correct.');
 
     $this->assertSame('2013-01-02T04:05:00', $node->field_test_date->value, 'Date field with text widget is correct');
-    $this->assertSame('1391357160', $node->field_test_datestamp->value, 'Date field with text widget is correct');
-    $this->assertSame('2015-03-04 06:07:00', $node->field_test_datetime->value, 'Date field with text widget is correct');
+    $this->assertSame('2014-02-02T16:06:00', $node->field_test_datestamp->value, 'Date field with text widget is correct');
+    $this->assertSame('2015-03-04T06:07:00', $node->field_test_datetime->value, 'Date field with text widget is correct');
 
     // Test that link fields are migrated.
     $this->assertIdentical('https://www.drupal.org/project/drupal', $node->field_test_link->uri);
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/datetime/src/Plugin/migrate/cckfield/d6/DateField.php
@@ -0,0 +1,56 @@
+<?php
+
+namespace Drupal\datetime\Plugin\migrate\cckfield\d6;
+
+use Drupal\migrate\Plugin\MigrationInterface;
+use Drupal\migrate_drupal\Plugin\migrate\cckfield\CckFieldPluginBase;
+
+/**
+ * @MigrateCckField(
+ *   id = "date",
+ *   type_map = {
+ *     "date" = "datetime",
+ *     "datestamp" =  "datetime",
+ *     "datetime" =  "datetime",
+ *   },
+ *   core = {6}
+ * )
+ */
+class DateField extends CckFieldPluginBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFieldFormatterMap() {
+    // See d6_field_formatter_settings.yml and CckFieldPluginBase
+    // processFieldFormatter().
+    return [];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function processCckFieldValues(MigrationInterface $migration, $field_name, $data) {
+
+    switch($data['type']) {
+      case 'date':
+        $from_format = 'Y-m-d\TH:i:s';
+        break;
+      case 'datestamp':
+        $from_format = 'U';
+        break;
+      case 'datetime':
+        $from_format = 'Y-m-d H:i:s';
+        break;
+    }
+    $process = [
+      'plugin' => 'format_date',
+      'from_format' => $from_format,
+      'to_format' => 'Y-m-d\TH:i:s',
+      'source' => $field_name,
+    ];
+
+    $migration->mergeProcessOfProperty($field_name, $process);
+  }
+
+}