Wrong order tax amounts displayed when using specific tax configuration

[jreinke]

Preconditions

1. Magento CE 2.1 with sample data installed
2. PHP 7 (does not matter IMHO)
3. MySQL 5.7 (does not matter IMHO)

Steps to reproduce

1. Go to Magento admin
2. Create the following tax rates (Stores > Tax Zones and Rates):

Tax Identifier	Country	Zip	State	Rate
Tax1	France	*	*	10%
Tax2	France	*	*	5%
Tax3	France	*	*	20%

3. Create the following tax rules (Stores > Tax Rules):

Name	Tax Rate	Customer Tax Class	Product Tax Class	Priority	Sort Order
Tax1	Tax1	Retail Customer	Taxable Goods	0	0
Tax2	Tax2	Retail Customer	Taxable Goods	1	0
Tax3	Tax3	Retail Customer	Taxable Goods	1	0

4. Enable full tax summary display in "Stores > Configuration > Sales > Tax > Orders, Invoices, Credit Memos Display Settings > Display Full Tax Summary"
5. Go to frontend and click on category "Gear > Bags"
6. Add product "Strive Shoulder Pack" to cart (qty = 1)
7. Go to checkout
8. Continue as guest or as authenticated user
9. Provide shipping address with country France (according to tax country configured in step 2)
10. Place order
11. Go to order details page

Expected result

Tax total amount should be equal to the sum of the tax details amounts (12.00 for this use case)

Actual result

Tax details sum is equal to 11.20

Thanks!

[choukalos]

Questions:

• What country is this for?
• Can you share details on what are the 3 taxes you need to collect?
• What is your tax configuration?
• Are product prices loaded including tax?
• What's your shipping origin set to?

Thanks!
Chuck

[jreinke]

Hi,

This is not for a specific purpose but this configuration comes with our internal test cases. France is just an example, you can test with another country if you want.

All other configurations are the Magento default ones. Nothing else has been modified. Just make a fresh install, follow the steps to reproduce and you should be able to reproduce the bug.

I had to debug this by myself and I think the bug may come from this code:

magento2/app/code/Magento/Tax/Model/Plugin/OrderSave.php

Line 98 in 99e85cb

$percentSum = 0;

$percentSum is never used while it should be instead of $rates['percent'].

A fix suggestion could look like this:

$percentSum = 0;
array_walk($taxRates, function($rate) use ($percentSum) {
    $percentSum += $rate['percent'];
});
foreach ($taxRates as $rate) {
    $realAmount = $rates['amount'] * $rate['percent'] / $percentSum;
    $realBaseAmount = $rates['base_amount'] * $rate['percent'] / $percentSum;
    $ratesIdQuoteItemId[$rates['id']][] = [
        'id' => $taxesArray['item_id'],
        'percent' => $rate['percent'],
        'code' => $rate['code'],
        'associated_item_id' => $taxesArray['associated_item_id'],
        'item_type' => $taxesArray['type'],
        'amount' => $rates['amount'],
        'base_amount' => $rates['base_amount'],
        'real_amount' => $realAmount,
        'real_base_amount' => $realBaseAmount,
    ];
}

Thanks

[jreinke]

Hi team,

Any feedback on this please?