diff --git a/CRM/Core/Payment.php b/CRM/Core/Payment.php
index 63ce4d9b5a31..cf31189d384d 100644
--- a/CRM/Core/Payment.php
+++ b/CRM/Core/Payment.php
@@ -1393,6 +1393,9 @@ public static function handlePaymentMethod($method, $params = array()) {
       $extension_instance_found = TRUE;
     }
 
+    // Call IPN alterIPNData hook to allow for custom processing of IPN data.
+    $IPNParams = array_merge($_GET, $_REQUEST);
+    CRM_Utils_Hook::postIPNProcess($IPNParams);
     if (!$extension_instance_found) {
       $message = "No extension instances of the '%1' payment processor were found.<br />" .
         "%2 method is unsupported in legacy payment processors.";
diff --git a/CRM/Utils/Hook.php b/CRM/Utils/Hook.php
index 92989a902534..e00b3f2f93e1 100644
--- a/CRM/Utils/Hook.php
+++ b/CRM/Utils/Hook.php
@@ -2473,4 +2473,17 @@ public static function alterMailingRecipients(&$mailingObject, &$criteria, $cont
     );
   }
 
+  /**
+   * ALlow Extensions to custom process IPN hook data such as sending Google Analyitcs information based on the IPN
+   * @param array $IPNData - Array of IPN Data
+   * @return mixed
+   */
+  public static function postIPNProcess(&$IPNData) {
+    return self::singleton()->invoke(array('IPNData'),
+      $IPNData, self::$_nullObject, self::$_nullObject,
+      self::$_nullObject, self::$_nullObject, self::$_nullObject,
+      'civicrm_postIPNProcess'
+    );
+  }
+
 }
diff --git a/tests/phpunit/CRM/Core/Payment/PayPalIPNTest.php b/tests/phpunit/CRM/Core/Payment/PayPalIPNTest.php
index 9de32d4ea3a8..c9862c05ec5e 100644
--- a/tests/phpunit/CRM/Core/Payment/PayPalIPNTest.php
+++ b/tests/phpunit/CRM/Core/Payment/PayPalIPNTest.php
@@ -37,6 +37,7 @@ class CRM_Core_Payment_PayPalIPNTest extends CiviUnitTestCase {
   protected $_contributionRecurID;
   protected $_contributionPageID;
   protected $_paymentProcessorID;
+  protected $_customFieldID;
   /**
    * IDs of entities created to support the tests.
    *
@@ -237,6 +238,7 @@ public function getPaypalTransaction() {
       'first_name' => 'Robert',
       'txn_id' => '8XA571746W2698126',
       'residence_country' => 'US',
+      'custom' => json_encode(['cgid' => 'test12345']),
     );
   }
 
@@ -249,4 +251,69 @@ public function getPaypalRecurSubsequentTransaction() {
     return array_merge($this->getPaypalRecurTransaction(), array('txn_id' => 'secondone'));
   }
 
+  /**
+   * Test IPN response updates contribution and invoice is attached in mail reciept
+   * Test also AlterIPNData intercepts at the right point and allows for custom processing
+   * The scenario is that a pending contribution exists and the IPN call will update it to completed.
+   * And also if Tax and Invoicing is enabled, this unit test ensure that invoice pdf is attached with email recipet
+   */
+  public function testhookAlterIPNDataOnIPNPaymentSuccess() {
+
+    $pendingStatusID = CRM_Core_PseudoConstant::getKey('CRM_Contribute_BAO_Contribution', 'contribution_status_id', 'Pending');
+    $completedStatusID = CRM_Core_PseudoConstant::getKey('CRM_Contribute_BAO_Contribution', 'contribution_status_id', 'Completed');
+    $params = array(
+      'payment_processor_id' => $this->_paymentProcessorID,
+      'contact_id' => $this->_contactID,
+      'trxn_id' => NULL,
+      'invoice_id' => $this->_invoiceID,
+      'contribution_status_id' => $pendingStatusID,
+      'is_email_receipt' => TRUE,
+    );
+    $this->_contributionID = $this->contributionCreate($params);
+    $this->createCustomField();
+    $contribution = $this->callAPISuccess('contribution', 'get', array('id' => $this->_contributionID, 'sequential' => 1));
+    // assert that contribution created before handling payment via paypal standard has no transaction id set and pending status
+    $this->assertEquals(NULL, $contribution['values'][0]['trxn_id']);
+    $this->assertEquals($pendingStatusID, $contribution['values'][0]['contribution_status_id']);
+    $this->hookClass->setHook('civicrm_postIPNProcess', array($this, 'hookCiviCRMAlterIPNData'));
+    global $_REQUEST;
+    $_REQUEST = array('q' => CRM_Utils_System::url('civicrm/payment/ipn/' . $this->_paymentProcessorID)) + $this->getPaypalTransaction();
+
+    $mut = new CiviMailUtils($this, TRUE);
+    $payment = CRM_Core_Payment::handlePaymentMethod('PaymentNotification', ['processor_id' => $this->_paymentProcessorID]);
+
+    $contribution = $this->callAPISuccess('contribution', 'get', array('id' => $this->_contributionID, 'sequential' => 1));
+    // assert that contribution is completed after getting response from paypal standard which has transaction id set and completed status
+    $this->assertEquals($_REQUEST['txn_id'], $contribution['values'][0]['trxn_id']);
+    $this->assertEquals($completedStatusID, $contribution['values'][0]['contribution_status_id']);
+    $this->assertEquals('test12345', $contribution['values'][0]['custom_' . $this->_customFieldID]);
+  }
+
+  /**
+   * Store Custom data passed in from the PayPalIPN in a custom field
+   */
+  public function hookCiviCRMAlterIPNData($data) {
+    if (!empty($data['custom'])) {
+      $customData = json_decode($data['custom'], TRUE);
+      $customField = $this->callAPISuccess('custom_field', 'get', ['label' => 'TestCustomFieldIPNHook']);
+      $this->callAPISuccess('contribution', 'create', ['id' => $this->_contributionID, 'custom_' . $customField['id'] => $customData['cgid']]);
+    }
+  }
+
+  /**
+   * @return array
+   */
+  protected function createCustomField() {
+    $customGroup = $this->customGroupCreate(array('extends' => 'Contribution'));
+    $fields = array(
+      'label' => 'TestCustomFieldIPNHook',
+      'data_type' => 'String',
+      'html_type' => 'Text',
+      'custom_group_id' => $customGroup['id'],
+    );
+    $field = CRM_Core_BAO_CustomField::create($fields);
+    $this->_customFieldID = $field->id;
+    return $customGroup;
+  }
+
 }