diff --git a/modules/order/commerce_order.install b/modules/order/commerce_order.install
index 8662ffbb73..cdf56467d0 100644
--- a/modules/order/commerce_order.install
+++ b/modules/order/commerce_order.install
@@ -73,3 +73,17 @@ function commerce_order_update_8204() {
   $update_manager = \Drupal::entityDefinitionUpdateManager();
   $update_manager->installFieldStorageDefinition('uses_legacy_adjustments', 'commerce_order_item', 'commerce_order', $storage_definition);
 }
+
+/**
+ * Add the 'total_paid' field to 'commerce_order' entities.
+ */
+function commerce_order_update_8205() {
+  $storage_definition = BaseFieldDefinition::create('commerce_price')
+    ->setLabel(t('Total paid'))
+    ->setDescription(t('The total paid price of the order.'))
+    ->setDisplayConfigurable('form', FALSE)
+    ->setDisplayConfigurable('view', TRUE);
+
+  $update_manager = \Drupal::entityDefinitionUpdateManager();
+  $update_manager->installFieldStorageDefinition('total_paid', 'commerce_order', 'commerce_order', $storage_definition);
+}
diff --git a/modules/order/src/Entity/Order.php b/modules/order/src/Entity/Order.php
index 7427531585..a7f8b3b1d4 100644
--- a/modules/order/src/Entity/Order.php
+++ b/modules/order/src/Entity/Order.php
@@ -4,6 +4,7 @@
 
 use Drupal\commerce\Entity\CommerceContentEntityBase;
 use Drupal\commerce_order\Adjustment;
+use Drupal\commerce_price\Price;
 use Drupal\commerce_store\Entity\StoreInterface;
 use Drupal\Core\Entity\EntityChangedTrait;
 use Drupal\Core\Entity\EntityStorageInterface;
@@ -402,6 +403,40 @@ public function getTotalPrice() {
     }
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function getTotalPaid() {
+    if (!$this->get('total_paid')->isEmpty()) {
+      return $this->get('total_paid')->first()->toPrice();
+    }
+    elseif ($total_price = $this->getTotalPrice()) {
+      // Provide a default without storing it, to avoid having to update
+      // the field if the order currency changes before the order is placed.
+      return new Price('0', $total_price->getCurrencyCode());
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setTotalPaid(Price $total_paid) {
+    $this->set('total_paid', $total_paid);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getBalance() {
+    if ($total_price = $this->getTotalPrice()) {
+      $balance = $total_price;
+      if ($total_paid = $this->getTotalPaid()) {
+        $balance = $balance->subtract($total_paid);
+      }
+      return $balance;
+    }
+  }
+
   /**
    * {@inheritdoc}
    */
@@ -688,6 +723,12 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
       ->setDisplayConfigurable('form', FALSE)
       ->setDisplayConfigurable('view', TRUE);
 
+    $fields['total_paid'] = BaseFieldDefinition::create('commerce_price')
+      ->setLabel(t('Total paid'))
+      ->setDescription(t('The total paid price of the order.'))
+      ->setDisplayConfigurable('form', FALSE)
+      ->setDisplayConfigurable('view', TRUE);
+
     $fields['state'] = BaseFieldDefinition::create('state')
       ->setLabel(t('State'))
       ->setDescription(t('The order state.'))
diff --git a/modules/order/src/Entity/OrderInterface.php b/modules/order/src/Entity/OrderInterface.php
index 84a9621057..457a8a6c87 100644
--- a/modules/order/src/Entity/OrderInterface.php
+++ b/modules/order/src/Entity/OrderInterface.php
@@ -3,6 +3,7 @@
 namespace Drupal\commerce_order\Entity;
 
 use Drupal\commerce_order\EntityAdjustableInterface;
+use Drupal\commerce_price\Price;
 use Drupal\commerce_store\Entity\StoreInterface;
 use Drupal\Core\Entity\ContentEntityInterface;
 use Drupal\Core\Entity\EntityChangedInterface;
@@ -275,6 +276,33 @@ public function recalculateTotalPrice();
    */
   public function getTotalPrice();
 
+  /**
+   * Gets the total paid price.
+   *
+   * @return \Drupal\commerce_price\Price|null
+   *   The total paid price, or NULL.
+   */
+  public function getTotalPaid();
+
+  /**
+   * Sets the total paid price.
+   *
+   * @param \Drupal\commerce_price\Price $total_paid
+   *   The total paid price.
+   */
+  public function setTotalPaid(Price $total_paid);
+
+  /**
+   * Gets the order balance.
+   *
+   * Calculated by subtracting the total paid price from the total price.
+   * Can be negative in case the order was overpaid.
+   *
+   * @return \Drupal\commerce_price\Price|null
+   *   The order balance, or NULL.
+   */
+  public function getBalance();
+
   /**
    * Gets the order state.
    *
diff --git a/modules/order/tests/src/Kernel/Entity/OrderTest.php b/modules/order/tests/src/Kernel/Entity/OrderTest.php
index b2d5a41e73..7bd5d718ac 100644
--- a/modules/order/tests/src/Kernel/Entity/OrderTest.php
+++ b/modules/order/tests/src/Kernel/Entity/OrderTest.php
@@ -97,6 +97,9 @@ protected function setUp() {
    * @covers ::getSubtotalPrice
    * @covers ::recalculateTotalPrice
    * @covers ::getTotalPrice
+   * @covers ::getTotalPaid
+   * @covers ::setTotalPaid
+   * @covers ::getBalance
    * @covers ::getState
    * @covers ::getRefreshState
    * @covers ::setRefreshState
@@ -140,6 +143,7 @@ public function testOrder() {
     $order = Order::create([
       'type' => 'default',
       'state' => 'completed',
+      'store_id' => $this->store->id(),
     ]);
     $order->save();
 
@@ -227,6 +231,15 @@ public function testOrder() {
     $order->clearAdjustments();
     $this->assertEquals($adjustments, $order->getAdjustments());
 
+    $this->assertEquals(new Price('0', 'USD'), $order->getTotalPaid());
+    $this->assertEquals(new Price('17.00', 'USD'), $order->getBalance());
+    $order->setTotalPaid(new Price('7.00', 'USD'));
+    $this->assertEquals(new Price('7.00', 'USD'), $order->getTotalPaid());
+    $this->assertEquals(new Price('10.00', 'USD'), $order->getBalance());
+    $order->setTotalPaid(new Price('27.00', 'USD'));
+    $this->assertEquals(new Price('27.00', 'USD'), $order->getTotalPaid());
+    $this->assertEquals(new Price('-10.00', 'USD'), $order->getBalance());
+
     $this->assertEquals('completed', $order->getState()->value);
 
     $order->setRefreshState(Order::REFRESH_ON_SAVE);
diff --git a/modules/payment/commerce_payment.services.yml b/modules/payment/commerce_payment.services.yml
index 3ae13d196b..0c7972d033 100644
--- a/modules/payment/commerce_payment.services.yml
+++ b/modules/payment/commerce_payment.services.yml
@@ -24,3 +24,7 @@ services:
   commerce_payment.options_builder:
     class: Drupal\commerce_payment\PaymentOptionsBuilder
     arguments: ['@entity_type.manager', '@string_translation']
+
+  commerce_payment.order_manager:
+    class: Drupal\commerce_payment\PaymentOrderManager
+    arguments: ['@entity_type.manager']
diff --git a/modules/payment/src/Entity/Payment.php b/modules/payment/src/Entity/Payment.php
index a87dcd1ad9..4774237885 100644
--- a/modules/payment/src/Entity/Payment.php
+++ b/modules/payment/src/Entity/Payment.php
@@ -311,6 +311,34 @@ public function preSave(EntityStorageInterface $storage) {
     }
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function postSave(EntityStorageInterface $storage, $update = TRUE) {
+    if ($this->isCompleted()) {
+      $payment_order_manager = \Drupal::service('commerce_payment.order_manager');
+      $payment_order_manager->updateTotalPaid($this->getOrder());
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function postDelete(EntityStorageInterface $storage, array $entities) {
+    parent::postDelete($storage, $entities);
+
+    // Multiple payments might reference the same order, make sure that each
+    // order is only updated once.
+    $orders = [];
+    foreach ($entities as $entity) {
+      $orders[$entity->getOrderId()] = $entity->getOrder();
+    }
+    $payment_order_manager = \Drupal::service('commerce_payment.order_manager');
+    foreach ($orders as $order) {
+      $payment_order_manager->updateTotalPaid($order);
+    }
+  }
+
   /**
    * {@inheritdoc}
    */
diff --git a/modules/payment/src/PaymentOrderManager.php b/modules/payment/src/PaymentOrderManager.php
new file mode 100644
index 0000000000..2541766461
--- /dev/null
+++ b/modules/payment/src/PaymentOrderManager.php
@@ -0,0 +1,54 @@
+<?php
+
+namespace Drupal\commerce_payment;
+
+use Drupal\commerce_order\Entity\OrderInterface;
+use Drupal\commerce_price\Price;
+use Drupal\Core\Entity\EntityTypeManagerInterface;
+
+class PaymentOrderManager implements PaymentOrderManagerInterface {
+
+  /**
+   * The payment storage.
+   *
+   * @var \Drupal\commerce_payment\PaymentStorageInterface
+   */
+  protected $paymentStorage;
+
+  /**
+   * Constructs a new PaymentOrderManager object.
+   *
+   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
+   *   The entity type manager.
+   */
+  public function __construct(EntityTypeManagerInterface $entity_type_manager) {
+    $this->paymentStorage = $entity_type_manager->getStorage('commerce_payment');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function updateTotalPaid(OrderInterface $order) {
+    $previous_total = $order->getTotalPaid();
+    if (!$previous_total) {
+      // A NULL total indicates an order that doesn't have any items yet.
+      return;
+    }
+    // The new total is always calculated from scratch, to properly handle
+    // orders that were created before the total_paid field was introduced.
+    $payments = $this->paymentStorage->loadMultipleByOrder($order);
+    /** @var \Drupal\commerce_price\Price $new_total */
+    $new_total = new Price('0', $previous_total->getCurrencyCode());
+    foreach ($payments as $payment) {
+      if ($payment->isCompleted()) {
+        $new_total = $new_total->add($payment->getBalance());
+      }
+    }
+
+    if (!$previous_total->equals($new_total)) {
+      $order->setTotalPaid($new_total);
+      $order->save();
+    }
+  }
+
+}
diff --git a/modules/payment/src/PaymentOrderManagerInterface.php b/modules/payment/src/PaymentOrderManagerInterface.php
new file mode 100644
index 0000000000..4761960bf8
--- /dev/null
+++ b/modules/payment/src/PaymentOrderManagerInterface.php
@@ -0,0 +1,22 @@
+<?php
+
+namespace Drupal\commerce_payment;
+
+use Drupal\commerce_order\Entity\OrderInterface;
+
+/**
+ * Updates orders based on payment information.
+ */
+interface PaymentOrderManagerInterface {
+
+  /**
+   * Recalculates the total paid price for the given order.
+   *
+   * The order will be saved if the total paid price has changed.
+   *
+   * @param \Drupal\commerce_order\Entity\OrderInterface $order
+   *   The order.
+   */
+  public function updateTotalPaid(OrderInterface $order);
+
+}
diff --git a/modules/payment/tests/src/Functional/DefaultPaymentAdminTest.php b/modules/payment/tests/src/Functional/DefaultPaymentAdminTest.php
index bec8bc008b..007812f1f2 100644
--- a/modules/payment/tests/src/Functional/DefaultPaymentAdminTest.php
+++ b/modules/payment/tests/src/Functional/DefaultPaymentAdminTest.php
@@ -153,6 +153,7 @@ public function testPaymentCreation() {
     $this->assertSession()->addressEquals($this->paymentUri);
     $this->assertSession()->pageTextContains('Completed');
 
+    \Drupal::entityTypeManager()->getStorage('commerce_payment')->resetCache([1]);
     /** @var \Drupal\commerce_payment\Entity\PaymentInterface $payment */
     $payment = Payment::load(1);
     $this->assertEquals($payment->getOrderId(), $this->order->id());
@@ -182,6 +183,7 @@ public function testPaymentCapture() {
     $this->assertSession()->pageTextNotContains('Authorization');
     $this->assertSession()->pageTextContains('Completed');
 
+    \Drupal::entityTypeManager()->getStorage('commerce_payment')->resetCache([$payment->id()]);
     $payment = Payment::load($payment->id());
     $this->assertEquals($payment->getState()->getLabel(), 'Completed');
   }
@@ -208,6 +210,7 @@ public function testPaymentRefund() {
     $this->assertSession()->pageTextNotContains('Completed');
     $this->assertSession()->pageTextContains('Refunded');
 
+    \Drupal::entityTypeManager()->getStorage('commerce_payment')->resetCache([$payment->id()]);
     $payment = Payment::load($payment->id());
     $this->assertEquals($payment->getState()->getLabel(), 'Refunded');
   }
@@ -233,6 +236,7 @@ public function testPaymentVoid() {
     $this->assertSession()->addressEquals($this->paymentUri);
     $this->assertSession()->pageTextContains('Authorization (Voided)');
 
+    \Drupal::entityTypeManager()->getStorage('commerce_payment')->resetCache([$payment->id()]);
     $payment = Payment::load($payment->id());
     $this->assertEquals($payment->getState()->getLabel(), 'Authorization (Voided)');
   }
@@ -258,6 +262,7 @@ public function testPaymentDelete() {
     $this->assertSession()->addressEquals($this->paymentUri);
     $this->assertSession()->pageTextNotContains('Authorization');
 
+    \Drupal::entityTypeManager()->getStorage('commerce_payment')->resetCache([$payment->id()]);
     $payment = Payment::load($payment->id());
     $this->assertNull($payment);
   }
diff --git a/modules/payment/tests/src/Functional/ManualPaymentAdminTest.php b/modules/payment/tests/src/Functional/ManualPaymentAdminTest.php
index c1a0a9ab07..d79cc40a52 100644
--- a/modules/payment/tests/src/Functional/ManualPaymentAdminTest.php
+++ b/modules/payment/tests/src/Functional/ManualPaymentAdminTest.php
@@ -110,6 +110,8 @@ public function testPaymentCreation() {
     $this->submitForm(['payment[amount][number]' => '100'], 'Add payment');
     $this->assertSession()->addressEquals($this->paymentUri);
     $this->assertSession()->pageTextContains('Pending');
+
+    \Drupal::entityTypeManager()->getStorage('commerce_payment')->resetCache([1]);
     /** @var \Drupal\commerce_payment\Entity\PaymentInterface $payment */
     $payment = Payment::load(1);
     $this->assertEquals($payment->getOrderId(), $this->order->id());
@@ -122,6 +124,8 @@ public function testPaymentCreation() {
     $this->submitForm(['payment[amount][number]' => '100', 'payment[received]' => TRUE], 'Add payment');
     $this->assertSession()->addressEquals($this->paymentUri);
     $this->assertSession()->pageTextContains('Completed');
+
+    \Drupal::entityTypeManager()->getStorage('commerce_payment')->resetCache([2]);
     /** @var \Drupal\commerce_payment\Entity\PaymentInterface $payment */
     $payment = Payment::load(2);
     $this->assertEquals($payment->getOrderId(), $this->order->id());
@@ -147,6 +151,7 @@ public function testPaymentReceive() {
     $this->assertSession()->pageTextNotContains('Pending');
     $this->assertSession()->pageTextContains('Completed');
 
+    \Drupal::entityTypeManager()->getStorage('commerce_payment')->resetCache([$payment->id()]);
     $payment = Payment::load($payment->id());
     $this->assertEquals($payment->getState()->getLabel(), 'Completed');
   }
@@ -168,8 +173,9 @@ public function testPaymentRefund() {
     $this->assertSession()->pageTextNotContains('Completed');
     $this->assertSession()->pageTextContains('Refunded');
 
+    \Drupal::entityTypeManager()->getStorage('commerce_payment')->resetCache([$payment->id()]);
     $payment = Payment::load($payment->id());
-    $this->assertEquals($payment->getState()->getLabel(), 'Refunded');
+    $this->assertEquals('Refunded', $payment->getState()->getLabel());
   }
 
   /**
@@ -188,6 +194,7 @@ public function testPaymentVoid() {
     $this->assertSession()->addressEquals($this->paymentUri);
     $this->assertSession()->pageTextContains('Voided');
 
+    \Drupal::entityTypeManager()->getStorage('commerce_payment')->resetCache([$payment->id()]);
     $payment = Payment::load($payment->id());
     $this->assertEquals($payment->getState()->getLabel(), 'Voided');
   }
diff --git a/modules/payment/tests/src/Kernel/Entity/PaymentTest.php b/modules/payment/tests/src/Kernel/Entity/PaymentTest.php
index e7a2a2b941..978e315754 100644
--- a/modules/payment/tests/src/Kernel/Entity/PaymentTest.php
+++ b/modules/payment/tests/src/Kernel/Entity/PaymentTest.php
@@ -3,6 +3,8 @@
 namespace Drupal\Tests\commerce_payment\Kernel\Entity;
 
 use Drupal\commerce_order\Entity\Order;
+use Drupal\commerce_order\Entity\OrderItem;
+use Drupal\commerce_order\Entity\OrderItemType;
 use Drupal\commerce_payment\Entity\PaymentGateway;
 use Drupal\commerce_payment\Entity\Payment;
 use Drupal\commerce_payment\Plugin\Commerce\PaymentType\PaymentDefault;
@@ -69,11 +71,29 @@ protected function setUp() {
     $user = $this->createUser();
     $this->user = $this->reloadEntity($user);
 
+    // An order item type that doesn't need a purchasable entity.
+    OrderItemType::create([
+      'id' => 'test',
+      'label' => 'Test',
+      'orderType' => 'default',
+    ])->save();
+
+    $order_item = OrderItem::create([
+      'title' => 'Membership subscription',
+      'type' => 'test',
+      'quantity' => 1,
+      'unit_price' => [
+        'number' => '30.00',
+        'currency_code' => 'USD',
+      ],
+    ]);
+    $order_item->save();
+
     $order = Order::create([
       'type' => 'default',
-      'mail' => $this->user->getEmail(),
       'uid' => $this->user->id(),
       'store_id' => $this->store->id(),
+      'order_items' => [$order_item],
     ]);
     $order->save();
     $this->order = $this->reloadEntity($order);
@@ -158,6 +178,42 @@ public function testPayment() {
     $this->assertTrue($payment->isCompleted());
   }
 
+  /**
+   * Tests the order integration (total_paid field).
+   *
+   * @covers ::postSave
+   * @covers ::postDelete
+   */
+  public function testOrderIntegration() {
+    $this->assertEquals(new Price('0', 'USD'), $this->order->getTotalPaid());
+    $this->assertEquals(new Price('30', 'USD'), $this->order->getBalance());
+
+    /** @var \Drupal\commerce_payment\Entity\PaymentInterface $payment */
+    $payment = Payment::create([
+      'type' => 'payment_default',
+      'payment_gateway' => 'example',
+      'order_id' => $this->order->id(),
+      'amount' => new Price('30', 'USD'),
+      'state' => 'completed',
+    ]);
+    $payment->save();
+    $this->order = $this->reloadEntity($this->order);
+    $this->assertEquals(new Price('30', 'USD'), $this->order->getTotalPaid());
+    $this->assertEquals(new Price('0', 'USD'), $this->order->getBalance());
+
+    $payment->setRefundedAmount(new Price('15', 'USD'));
+    $payment->setState('partially_refunded');
+    $payment->save();
+    $this->order = $this->reloadEntity($this->order);
+    $this->assertEquals(new Price('15', 'USD'), $this->order->getTotalPaid());
+    $this->assertEquals(new Price('15', 'USD'), $this->order->getBalance());
+
+    $payment->delete();
+    $this->order = $this->reloadEntity($this->order);
+    $this->assertEquals(new Price('0', 'USD'), $this->order->getTotalPaid());
+    $this->assertEquals(new Price('30', 'USD'), $this->order->getBalance());
+  }
+
   /**
    * Tests the timestamp generation on preSave.
    *