Drupal Commerce 3: How to get the applied tax (VAT) rates from OrderItem / Order programmatically

Finding information about getting the tax from Drupal Commerce 3 Orders / Oder Items programmatically, was quite difficult. So I decided to write a short Blog entry and snippet on the topic.

The key information here is, that tax is an Adjustment type and based on the EntityAdjustableInterface:

/**
 * Defines an interface for objects that contain adjustments.
 *
 * Adjustments store promotions, taxes, fees, shipping costs.
 * They can be calculated on the order level (based on the order subtotal),
 * or on the order item level (based on the order item total).
 *
 * if $order_item->usesLegacyAdjustments() is true, the order item adjustments
 * were calculated based on the order item unit price, which was the default
 * logic prior to Commerce 2.8, changed in #2980713.
 *
 * Adjustments are always displayed in the order total summary, below
 * the subtotal. They are not shown as a part of the order item prices.
 * To get the order item total price with adjustments included, use
 * $order_item->getAdjustedTotalPrice().
 *
 * @see \Drupal\commerce_order\Entity\OrderInterfaceEntity
 * @see \Drupal\commerce_order\Entity\OrderItemInterfaceEntity
 */
interface EntityAdjustableInterface extends EntityInterface {
  ...
}

It's important to read the information about the different levels: Order and OrderItem!

Setting, adding, removing adjustments is typically a (complicated) module job, for example in the commerce submodules commerce_promition, commerce_tax and contrib module like commerce_giftcard.

What we want is getAdjustments():

  /**
   * Gets the adjustments.
   *
   * @param string[] $adjustment_types
   *   The adjustment types to include.
   *   Examples: fee, promotion, tax. Defaults to all adjustment types.
   *
   * @return \Drupal\commerce_order\Adjustment[]
   *   The adjustments.
   */
  public function getAdjustments(array $adjustment_types = []);

And as you can see in the documentation, you can filter by adjustment type, so we use:

// For the order:
$order->getAdjustments(['tax'])

// For order items:
$order->getAdjustments(['tax'])

to get the applied tax(es).

This returns an array with Objects of type \Drupal\commerce_order\Adjustment like this:

 array:1 [▼
  0 => Drupal\commerce_order\Adjustment {#6494 ▼
    #type: "tax"
    #label: "MwSt."
    #amount: Drupal\commerce_price\Price {#6495 ▼
      #number: "3.40"
      #currencyCode: "EUR"
    }
    #percentage: "0.19"
    #sourceId: "european_union_vat|de|standard"
    #included: true
    #locked: false
  }
]

And there you go - here are your absolute and percentage taxes applied!