diff --git a/modules/checkout/src/Plugin/Commerce/CheckoutFlow/CheckoutFlowBase.php b/modules/checkout/src/Plugin/Commerce/CheckoutFlow/CheckoutFlowBase.php
index 98cfca23c7..774d9c366b 100644
--- a/modules/checkout/src/Plugin/Commerce/CheckoutFlow/CheckoutFlowBase.php
+++ b/modules/checkout/src/Plugin/Commerce/CheckoutFlow/CheckoutFlowBase.php
@@ -246,11 +246,17 @@ public function getFormId() {
    * {@inheritdoc}
    */
   public function buildForm(array $form, FormStateInterface $form_state, $step_id = NULL) {
-    // The $step_id argument is optional only because PHP disallows adding required
-    // arguments to an existing interface's method.
+    // The $step_id argument is optional only because PHP disallows adding
+    // required arguments to an existing interface's method.
     if (empty($step_id)) {
       throw new \InvalidArgumentException('The $step_id cannot be empty.');
     }
+    if ($form_state->isRebuilding()) {
+      // Ensure a fresh order, in case an ajax submit has modified it.
+      $order_storage = $this->entityTypeManager->getStorage('commerce_order');
+      $this->order = $order_storage->load($this->order->id());
+    }
+
     $steps = $this->getVisibleSteps();
     $form['#tree'] = TRUE;
     $form['#step_id'] = $step_id;
diff --git a/modules/promotion/src/Element/CouponRedemptionForm.php b/modules/promotion/src/Element/CouponRedemptionForm.php
index 42b7683818..2d4798c879 100644
--- a/modules/promotion/src/Element/CouponRedemptionForm.php
+++ b/modules/promotion/src/Element/CouponRedemptionForm.php
@@ -6,21 +6,27 @@
 use Drupal\commerce_order\Entity\OrderInterface;
 use Drupal\commerce_promotion\Entity\CouponInterface;
 use Drupal\commerce_promotion\Entity\PromotionInterface;
+use Drupal\Component\Utility\NestedArray;
 use Drupal\Core\Form\FormStateInterface;
 
 /**
- * Provides a form element for embedding the coupon redemption form.
+ * Provides a form element for redeeming a coupon.
  *
  * Usage example:
  * @code
- * $form['coupons'] = [
+ * $form['coupon'] = [
  *   '#type' => 'commerce_coupon_redemption_form',
- *   // The order to which the coupon will be applied to.
- *   '#order' => $order,
+ *   '#title' => t('Coupon code'),
+ *   '#default_value' => $coupon_id,
+ *   '#order_id' => $order_id,
  * ];
  * @endcode
+ * The element value ($form_state->getValue('coupon')) will be the
+ * coupon ID. Note that the order is not saved if the element was
+ * submitted as a result of the main form being submitted. It is the
+ * responsibility of the caller to update the order in that case.
  *
- * @RenderElement("commerce_coupon_redemption_form")
+ * @FormElement("commerce_coupon_redemption_form")
  */
 class CouponRedemptionForm extends CommerceElementBase {
 
@@ -30,22 +36,20 @@ class CouponRedemptionForm extends CommerceElementBase {
   public function getInfo() {
     $class = get_class($this);
     return [
-      // The order to which the coupon will be applied to.
-      '#order' => NULL,
       '#title' => t('Coupon code'),
       '#description' => t('Enter your coupon code here.'),
       '#submit_title' => t('Apply coupon'),
+      '#submit_message' => t('Coupon applied'),
+      '#remove_title' => t('Remove coupon'),
+      // The coupon ID.
+      '#default_value' => NULL,
+      '#order_id' => NULL,
       '#process' => [
-        [$class, 'attachElementSubmit'],
         [$class, 'processForm'],
       ],
       '#element_validate' => [
-        [$class, 'validateElementSubmit'],
         [$class, 'validateForm'],
       ],
-      '#commerce_element_submit' => [
-        [$class, 'submitForm'],
-      ],
       '#theme_wrappers' => ['container'],
     ];
   }
@@ -61,26 +65,28 @@ public function getInfo() {
    *   The complete form structure.
    *
    * @throws \InvalidArgumentException
-   *   Thrown when the #order property is empty or invalid entity.
+   *   Thrown when the #order_id property is empty or invalid.
    *
    * @return array
    *   The processed form element.
    */
   public static function processForm(array $element, FormStateInterface $form_state, array &$complete_form) {
-    if (empty($element['#order'])) {
-      throw new \InvalidArgumentException('The commerce_coupon_redemption_form element requires the #order property.');
+    if (empty($element['#order_id'])) {
+      throw new \InvalidArgumentException('The commerce_coupon_redemption_form element requires the #order_id property.');
     }
-    if (!$element['#order'] instanceof OrderInterface) {
-      throw new \InvalidArgumentException('The commerce_coupon_redemption_form #order property must be an order entity.');
+    $order_storage = \Drupal::entityTypeManager()->getStorage('commerce_order');
+    $order = $order_storage->load($element['#order_id']);
+    if (!$order instanceof OrderInterface) {
+      throw new \InvalidArgumentException('The commerce_coupon_redemption #order_id must be a valid order ID.');
     }
 
+    $has_coupons = !$order->get('coupons')->isEmpty();
     $id_prefix = implode('-', $element['#parents']);
     // @todo We cannot use unique IDs, or multiple elements on a page currently.
     // @see https://www.drupal.org/node/2675688
     // $wrapper_id = Html::getUniqueId($id_prefix . '-ajax-wrapper');
     $wrapper_id = $id_prefix . '-ajax-wrapper';
 
-    $form_state->set('order', $element['#order']);
     $element = [
       '#tree' => TRUE,
       '#prefix' => '<div id="' . $wrapper_id . '">',
@@ -92,21 +98,96 @@ public static function processForm(array $element, FormStateInterface $form_stat
       '#type' => 'textfield',
       '#title' => $element['#title'],
       '#description' => $element['#description'],
+      '#access' => !$has_coupons,
     ];
     $element['apply'] = [
       '#type' => 'submit',
       '#value' => $element['#submit_title'],
       '#name' => 'apply_coupon',
       '#limit_validation_errors' => [
-        array_merge($element['#parents'], ['code']),
+        $element['#parents'],
+      ],
+      '#submit' => [
+        [get_called_class(), 'applyCoupon'],
       ],
+      '#ajax' => [
+        'callback' => [get_called_class(), 'ajaxRefresh'],
+        'wrapper' => $element['#wrapper_id'],
+      ],
+      '#access' => !$has_coupons,
+    ];
+    $element['remove'] = [
+      '#type' => 'submit',
+      '#value' => $element['#remove_title'],
+      '#name' => 'remove_coupon',
+      '#ajax' => [
+        'callback' => [get_called_class(), 'ajaxRefresh'],
+        'wrapper' => $element['#wrapper_id'],
+      ],
+      '#weight' => 50,
+      '#limit_validation_errors' => [
+        $element['#parents'],
+      ],
+      '#submit' => [
+        [get_called_class(), 'removeCoupon'],
+      ],
+      '#access' => $has_coupons,
     ];
 
     return $element;
   }
 
   /**
-   * Validates the coupon redemption form.
+   * Ajax callback.
+   */
+  public static function ajaxRefresh(array $form, FormStateInterface $form_state) {
+    $parents = $form_state->getTriggeringElement()['#parents'];
+    array_pop($parents);
+    return NestedArray::getValue($form, $parents);
+  }
+
+  /**
+   * Apply coupon submit callback.
+   */
+  public static function applyCoupon(array $form, FormStateInterface $form_state) {
+    $triggering_element = $form_state->getTriggeringElement();
+    $parents = $triggering_element['#parents'];
+    array_pop($parents);
+    $element = NestedArray::getValue($form, $parents);
+
+    $entity_type_manager = \Drupal::entityTypeManager();
+    $order_storage = $entity_type_manager->getStorage('commerce_order');
+    /** @var \Drupal\commerce_order\Entity\OrderInterface $order */
+    $order = $order_storage->load($element['#order_id']);
+
+    $coupon = $form_state->getValue($parents);
+    $order->get('coupons')->appendItem($coupon);
+    $order->save();
+    $form_state->setRebuild();
+    drupal_set_message($element['#submit_message']);
+  }
+
+  /**
+   * Remove coupon submit callback.
+   */
+  public static function removeCoupon(array $form, FormStateInterface $form_state) {
+    $triggering_element = $form_state->getTriggeringElement();
+    $parents = $triggering_element['#parents'];
+    array_pop($parents);
+    $element = NestedArray::getValue($form, $parents);
+
+    $entity_type_manager = \Drupal::entityTypeManager();
+    $order_storage = $entity_type_manager->getStorage('commerce_order');
+    /** @var \Drupal\commerce_order\Entity\OrderInterface $order */
+    $order = $order_storage->load($element['#order_id']);
+
+    $order->get('coupons')->setValue([]);
+    $order->save();
+    $form_state->setRebuild();
+  }
+
+  /**
+   * Validates the coupon redemption element.
    *
    * @param array $element
    *   The form element.
@@ -119,11 +200,12 @@ public static function validateForm(array &$element, FormStateInterface $form_st
     if (empty($coupon_code)) {
       return;
     }
-    $code_path = implode('][', $coupon_parents);
-    /** @var \Drupal\commerce_order\Entity\OrderInterface $order */
-    $order = $form_state->get('order');
     $entity_type_manager = \Drupal::entityTypeManager();
+    $code_path = implode('][', $coupon_parents);
 
+    $order_storage = $entity_type_manager->getStorage('commerce_order');
+    /** @var \Drupal\commerce_order\Entity\OrderInterface $order */
+    $order = $order_storage->load($element['#order_id']);
     /** @var \Drupal\commerce_promotion\CouponStorageInterface $coupon_storage */
     $coupon_storage = $entity_type_manager->getStorage('commerce_promotion_coupon');
     $coupon = $coupon_storage->loadByCode($coupon_code);
@@ -131,7 +213,6 @@ public static function validateForm(array &$element, FormStateInterface $form_st
       $form_state->setErrorByName($code_path, t('Coupon is invalid'));
       return;
     }
-
     foreach ($order->get('coupons') as $item) {
       if ($item->target_id == $coupon->id()) {
         $form_state->setErrorByName($code_path, t('Coupon has already been redeemed'));
@@ -142,7 +223,6 @@ public static function validateForm(array &$element, FormStateInterface $form_st
     $order_type_storage = $entity_type_manager->getStorage('commerce_order_type');
     /** @var \Drupal\commerce_promotion\PromotionStorageInterface $promotion_storage */
     $promotion_storage = $entity_type_manager->getStorage('commerce_promotion');
-
     /** @var \Drupal\commerce_order\Entity\OrderTypeInterface $order_type */
     $order_type = $order_type_storage->load($order->bundle());
     $promotion = $promotion_storage->loadByCoupon($order_type, $order->getStore(), $coupon);
@@ -150,47 +230,16 @@ public static function validateForm(array &$element, FormStateInterface $form_st
       $form_state->setErrorByName($code_path, t('Coupon is invalid'));
       return;
     }
-
     if (!self::couponApplies($order, $promotion, $coupon)) {
       $form_state->setErrorByName($code_path, t('Coupon is invalid'));
       return;
     }
-  }
-
-  /**
-   * Submits the coupon redemption form.
-   *
-   * @param array $element
-   *   The form element.
-   * @param \Drupal\Core\Form\FormStateInterface $form_state
-   *   The current state of the form.
-   */
-  public static function submitForm(array &$element, FormStateInterface $form_state) {
-    $coupon_parents = array_merge($element['#parents'], ['code']);
-    $coupon_code = $form_state->getValue($coupon_parents);
-    /** @var \Drupal\commerce_order\Entity\OrderInterface $order */
-    $order = $form_state->get('order');
-    $entity_type_manager = \Drupal::entityTypeManager();
-    $order_type_storage = $entity_type_manager->getStorage('commerce_order_type');
-    /** @var \Drupal\commerce_promotion\PromotionStorageInterface $promotion_storage */
-    $promotion_storage = $entity_type_manager->getStorage('commerce_promotion');
-    /** @var \Drupal\commerce_promotion\CouponStorageInterface $coupon_storage */
-    $coupon_storage = $entity_type_manager->getStorage('commerce_promotion_coupon');
 
-    $coupon = $coupon_storage->loadByCode($coupon_code);
-    /** @var \Drupal\commerce_order\Entity\OrderTypeInterface $order_type */
-    $order_type = $order_type_storage->load($order->bundle());
-    $promotion = $promotion_storage->loadByCoupon($order_type, $order->getStore(), $coupon);
-
-    if (self::couponApplies($order, $promotion, $coupon)) {
-      $order->get('coupons')->appendItem($coupon);
-      $order->save();
-      drupal_set_message(t('Coupon applied'));
-    }
+    $form_state->setValueForElement($element, $coupon);
   }
 
   /**
-   * Checks if a coupon applies.
+   * Checks whether a coupon applies.
    *
    * @param \Drupal\commerce_order\Entity\OrderInterface $order
    *   The order.
diff --git a/modules/promotion/tests/modules/commerce_promotion_test/commerce_promotion_test.module b/modules/promotion/tests/modules/commerce_promotion_test/commerce_promotion_test.module
index 531a063800..ea6554a826 100644
--- a/modules/promotion/tests/modules/commerce_promotion_test/commerce_promotion_test.module
+++ b/modules/promotion/tests/modules/commerce_promotion_test/commerce_promotion_test.module
@@ -13,13 +13,13 @@ use Drupal\Core\Form\FormStateInterface;
 function commerce_promotion_test_form_views_form_commerce_cart_form_default_alter(&$form, FormStateInterface $form_state, $form_id) {
   // We know that view forms are build on the base ID plus arguments.
   $order_id = substr($form_id, strlen('views_form_commerce_cart_form_default_'));
-  $order = \Drupal::entityTypeManager()->getStorage('commerce_order')->load($order_id);
 
   $form['coupons'] = [
     '#type' => 'commerce_coupon_redemption_form',
-    '#order' => $order,
+    '#order_id' => $order_id,
     '#title' => t('Promotion code'),
     '#description' => t('Enter your promotion code to redeem a discount.'),
     '#submit_title' => t('Apply'),
+    '#remove_title' => t('Remove promotion'),
   ];
 }
diff --git a/modules/promotion/tests/src/Functional/CouponRedemptionTest.php b/modules/promotion/tests/src/Functional/CouponRedemptionTest.php
index 6e95e3cf96..010e75ee3e 100644
--- a/modules/promotion/tests/src/Functional/CouponRedemptionTest.php
+++ b/modules/promotion/tests/src/Functional/CouponRedemptionTest.php
@@ -125,11 +125,15 @@ public function testCouponRedemption() {
 
     $this->getSession()->getPage()->fillField('coupons[code]', $existing_coupon->getCode());
     $this->getSession()->getPage()->pressButton('Apply');
+
     $this->assertSession()->pageTextContains('Coupon applied');
 
-    $this->getSession()->getPage()->fillField('coupons[code]', $existing_coupon->getCode());
-    $this->getSession()->getPage()->pressButton('Apply');
-    $this->assertSession()->pageTextContains('Coupon has already been redeemed');
+    $this->assertSession()->fieldNotExists('coupons[code]');
+    $this->assertSession()->buttonNotExists('Apply');
+    $this->getSession()->getPage()->pressButton('Remove promotion');
+
+    $this->assertSession()->fieldExists('coupons[code]');
+    $this->assertSession()->buttonExists('Apply');
   }
 
 }