How can I allow a Configurable product price (tax) to apply as per tax class of simple (child) product in Magento 2

Question

Magento 2 version 2.2.2

Steps to set tax rules: Create a configurable product, which has two simple (child) products. Configurable product is set as taxable with 20% tax setup. First simple product is set as taxable with 20% tax setup. Second simple product is set as no tax i.e. 0% tax. Add second product through configurable options to cart.

Actual result: Tax of 20% is being applied in cart for the second simple product.

Expected result: 0% tax should be applied for the second simple product.

How can I modify this to achieve my requirement?

Answer 1

I was having the same issue due to UK VAT rules and found several magento bug created on github but no actual fix.

So then while looking for a workaround I have built a module to change the Magento behaviour according to our requirement.

Basically we need to update the definition of mapItem method of class Magento\Tax\Model\Sales\Total\Quote\CommonTaxCollector

For that we need to override 2 magento classes i.e. write preference in di.xml

<preference for="Magento\Tax\Model\Sales\Total\Quote\CommonTaxCollector" type="VendorName\MagentoChildProductTaxExtend\Preference\Tax\Model\Sales\Total\Quote\CommonTaxCollector"/>
<preference for="Magento\Tax\Model\Sales\Total\Quote\Tax" type="VendorName\MagentoChildProductTaxExtend\Preference\Tax\Model\Sales\Total\Quote\Tax"/>

Now in mapItem method of class VendorName\MagentoChildProductTaxExtend\Preference\Tax\Model\Sales\Total\Quote\CommonTaxCollector in line 211, we need to replace the $item->getProduct()->getTaxClassId() with the child product tax class id.

For that, we can change to these lines of code in our own class -

    $taxClassId = $item->getProduct()->getTaxClassId();
    if($item->getHasChildren()) {
        foreach ($item->getChildren() as $child) {
            $taxClassId = $child->getProduct()->getTaxClassId();
        }
    }
    /** @var \Magento\Tax\Api\Data\QuoteDetailsItemInterface $itemDataObject */
    $itemDataObject = $itemDataObjectFactory->create();
    $itemDataObject->setCode($item->getTaxCalculationItemId())
        ->setQuantity($item->getQty())
        ->setTaxClassKey(
            $this->taxClassKeyDataObjectFactory->create()
                ->setType(TaxClassKeyInterface::TYPE_ID)
                //->setValue($item->getProduct()->getTaxClassId())
                ->setValue($taxClassId)
        )
        ->setIsTaxIncluded($priceIncludesTax)
        ->setType(self::ITEM_TYPE_PRODUCT);

Create your own module and add those codes, this works in every tax related section in magento, Tested on Ver 2.2.2

Cheers!!

Answer 2

You can also create a plugin for that

di.xml

<type name="Magento\Tax\Model\Sales\Total\Quote\CommonTaxCollector">
    <plugin name="child_tax" type="Vendor\ModuleName\Plugin\ChildTaxClass" sortOrder="1" />
</type>

ChildTaxClass.php

namespace Vendor\ModuleName\Plugin;
class ChildTaxClass
{
/**
 * @var \Magento\Tax\Api\Data\TaxClassKeyInterfaceFactory
 */
private $taxClassKeyDataObjectFactory;

/**
 * ChildTaxClass constructor.
 * @param \Magento\Tax\Api\Data\TaxClassKeyInterfaceFactory $taxClassKeyDataObjectFactory
 */
public function __construct(
    \Magento\Tax\Api\Data\TaxClassKeyInterfaceFactory $taxClassKeyDataObjectFactory
) {
    $this->taxClassKeyDataObjectFactory = $taxClassKeyDataObjectFactory;
}

/**
 * @param \Magento\Tax\Model\Sales\Total\Quote\CommonTaxCollector $subject
 * @param callable $proceed
 * @param \Magento\Tax\Api\Data\QuoteDetailsItemInterfaceFactory $itemDataObjectFactory
 * @param \Magento\Quote\Model\Quote\Item\AbstractItem $item
 * @param $priceIncludesTax
 * @param $useBaseCurrency
 * @param null $parentCode
 * @return \Magento\Quote\Model\Quote\Item\AbstractItem|\Magento\Tax\Api\Data\QuoteDetailsItemInterface
 */
public function aroundMapItem(
    \Magento\Tax\Model\Sales\Total\Quote\CommonTaxCollector $subject,
    callable $proceed,
    \Magento\Tax\Api\Data\QuoteDetailsItemInterfaceFactory $itemDataObjectFactory,
    \Magento\Quote\Model\Quote\Item\AbstractItem $item,
    $priceIncludesTax,
    $useBaseCurrency,
    $parentCode = null
) {

    $taxClassId = $item->getProduct()->getTaxClassId();
    if ($item->getHasChildren()) {
        foreach ($item->getChildren() as $child) {
            $taxClassId = $child->getProduct()->getTaxClassId();
        }
    }

    // call method
    /** @var \Magento\Tax\Api\Data\QuoteDetailsItemInterface $item */
    $item = $proceed(
        $itemDataObjectFactory,
        $item,
        $priceIncludesTax,
        $useBaseCurrency,
        $parentCode
    );

    // Set tax class from child (if available)
    $item->setTaxClassId($taxClassId);
    $item->setTaxClassKey(
        $this->taxClassKeyDataObjectFactory->create()
            ->setType(\Magento\Tax\Api\Data\TaxClassKeyInterface::TYPE_ID)
            ->setValue($taxClassId)
    );
    return $item;
}

}

Answer 3

i have the same problem on Magento 1 with UK product, different size have different tax rate.

exemple : Configurable (global 20% tax) - Simple 1 (global 20% tax, but on UK 0% tax) - Simple 2 (global 20% tax, but on UK 20% tax)

in method Mage_Tax_Model_Sales_Total_Quote_Tax::_totalBaseProcessItemTax, dont forget to add a config to disable this functionality

///// BEGIN OLD
//$taxRateRequest->setProductClassId($item->getProduct()->getTaxClassId());
///// BEGIN OLD
///// BEGIN AKOA
$configEnable = Mage::getStoreConfigFlag('tax/calculation/tax_rate_on_simple_enable', $item->getStoreId());
if ($configEnable && $item->getHasChildren()) {
    $children = $item->getChildren();
    foreach ($children as $childItem) {
        $taxRateRequest->setProductClassId($childItem->getProduct()->getTaxClassId());
        break;
    }
} else {
    $taxRateRequest->setProductClassId($item->getProduct()->getTaxClassId());
}
///// BEGIN AKOA

Answer 4

From Magento 2.3.2 the tax that is applied to a simple child product is now based on the tax class of that product. Previously, Magento based the tax for a child product on the tax class of its parent product.

So better way to fix this is to upgrade the version to match 2.3.2.

Best of LUCK!!