diff --git a/src/Normalizer/JsonApiDocumentTopLevelNormalizer.php b/src/Normalizer/JsonApiDocumentTopLevelNormalizer.php
index 0c36340..0d9940b 100644
--- a/src/Normalizer/JsonApiDocumentTopLevelNormalizer.php
+++ b/src/Normalizer/JsonApiDocumentTopLevelNormalizer.php
@@ -79,13 +79,18 @@ class JsonApiDocumentTopLevelNormalizer extends NormalizerBase implements Denorm
    * {@inheritdoc}
    */
   public function denormalize($data, $class, $format = NULL, array $context = []) {
+    // Validate a few common errors in document formatting.
+    $this->validateRequestBody($data);
+
     $context += [
       'on_relationship' => $this->currentContext->isOnRelationship(),
     ];
     $normalized = [];
+
     if (!empty($data['data']['attributes'])) {
       $normalized = $data['data']['attributes'];
     }
+
     if (!empty($data['data']['relationships'])) {
       // Turn all single object relationship data fields into an array of objects.
       $relationships = array_map(function ($relationship) {
@@ -273,4 +278,18 @@ class JsonApiDocumentTopLevelNormalizer extends NormalizerBase implements Denorm
     return $context;
   }
 
+  /**
+   * Performs mimimal validation of the document.
+   */
+  public function validateRequestBody($document) {
+    // Ensure that the relationships key was not placed in the top level.
+    if (isset($document['relationships']) && !empty($document['relationships'])) {
+      throw new BadRequestHttpException("Found \"relationships\" within the document's top level. The \"relationships\" key must be within resource object.");
+    }
+    // Ensure that the resource object contains the "type" key.
+    if (!isset($document['data']['type'])) {
+      throw new BadRequestHttpException("Resource object must include a \"type\".");
+    }
+  }
+
 }
diff --git a/tests/src/Functional/JsonApiFunctionalTest.php b/tests/src/Functional/JsonApiFunctionalTest.php
index f6441c7..4f47213 100644
--- a/tests/src/Functional/JsonApiFunctionalTest.php
+++ b/tests/src/Functional/JsonApiFunctionalTest.php
@@ -581,6 +581,39 @@ class JsonApiFunctionalTest extends JsonApiFunctionalTestBase {
     $this->assertEquals(422, $response->getStatusCode());
     $this->assertNotEmpty($created_response['errors']);
     $this->assertEquals('Unprocessable Entity', $created_response['errors'][0]['title']);
+    // 6.1 Relationships are not included in "data".
+    $malformed_body = $body;
+    unset($malformed_body['data']['relationships']);
+    $malformed_body['relationships'] = $body['data']['relationships'];
+    $response = $this->request('POST', $collection_url, [
+      'body' => Json::encode($malformed_body),
+      'auth' => [$this->user->getUsername(), $this->user->pass_raw],
+      'headers' => [
+        'Accept' => 'application/vnd.api+json',
+        'Content-Type' => 'application/vnd.api+json',
+      ],
+    ]);
+    $created_response = Json::decode((string) $response->getBody());
+    $this->assertEquals(400, $response->getStatusCode());
+    $this->assertNotEmpty($created_response['errors']);
+    $this->assertEquals("Bad Request", $created_response['errors'][0]['title']);
+    $this->assertEquals("Found \"relationships\" within the document's top level. The \"relationships\" key must be within resource object.", $created_response['errors'][0]['detail']);
+    // 6.2 "type" not included in "data"
+    $missing_type = $body;
+    unset($missing_type['data']['type']);
+    $response = $this->request('POST', $collection_url, [
+      'body' => Json::encode($missing_type),
+      'auth' => [$this->user->getUsername(), $this->user->pass_raw],
+      'headers' => [
+        'Accept' => 'application/vnd.api+json',
+        'Content-Type' => 'application/vnd.api+json',
+      ],
+    ]);
+    $created_response = Json::decode((string) $response->getBody());
+    $this->assertEquals(400, $response->getStatusCode());
+    $this->assertNotEmpty($created_response['errors']);
+    $this->assertEquals("Bad Request", $created_response['errors'][0]['title']);
+    $this->assertEquals("Resource object must include a \"type\".", $created_response['errors'][0]['detail']);
     // 7. Successful PATCH.
     $body = [
       'data' => [
diff --git a/tests/src/Kernel/Normalizer/JsonApiDocumentTopLevelNormalizerTest.php b/tests/src/Kernel/Normalizer/JsonApiDocumentTopLevelNormalizerTest.php
index 6d1afc9..77e3b45 100644
--- a/tests/src/Kernel/Normalizer/JsonApiDocumentTopLevelNormalizerTest.php
+++ b/tests/src/Kernel/Normalizer/JsonApiDocumentTopLevelNormalizerTest.php
@@ -444,7 +444,7 @@ class JsonApiDocumentTopLevelNormalizerTest extends JsonapiKernelTestBase {
    * @covers ::denormalize
    */
   public function testDenormalize() {
-    $payload = '{"type":"article", "data":{"attributes":{"title":"Testing article"}}}';
+    $payload = '{"data":{"type":"article","attributes":{"title":"Testing article"}}}';
 
     list($request, $resource_type) = $this->generateProphecies('node', 'article', 'id');
     $node = $this
@@ -554,8 +554,8 @@ class JsonApiDocumentTopLevelNormalizerTest extends JsonapiKernelTestBase {
    */
   public function testDenormalizeInvalidTypeAndNoType() {
     $payload_data = [
-      'type' => 'node--article',
       'data' => [
+        'type' => 'node--article',
         'attributes' => [
           'title' => 'Testing article',
           'id' => '33095485-70D2-4E51-A309-535CC5BC0115',
@@ -631,8 +631,8 @@ class JsonApiDocumentTopLevelNormalizerTest extends JsonapiKernelTestBase {
 
     $node = [
       [
-        'type' => 'node--article',
         'data' => [
+          'type' => 'node--article',
           'attributes' => [
             'title' => 'Testing article',
             'id' => '33095485-70D2-4E51-A309-535CC5BC0115',