A client requested that discounts displayed in the shopping cart should be shown including tax/vat. The relevant tax settings at the time were:

  • Apply Customer Tax: After Discount
  • Apply Discount on Prices: Excluding Tax

We subsequently changed these to...

  • Apply Customer Tax: Before Discount
  • Apply Discount on Prices: Including Tax

....but whilst the discount is now shown including tax/vat, the tax/vat amount is now displayed without taking the discount into account.

The settings that I thought would give us what we want are:

  • Apply Customer Tax: After Discount
  • Apply Discount on Prices: Including Tax

....but whilst this shows the discount including tax/vat, the grand total and vat figures are now incorrect and I receive following warning message (despite the settings not being ones which should generate the warning according to http://www.magentocommerce.com/knowledge-base/entry/magento-ce-18-ee-113-tax-calc):

Warning tax discount configuration might result in different discounts than a customer might expect

I've now established that the tax/vat figure is incorrect with these settings because when calculating product tax/vat it is first subtracting the GROSS discount, rather than net. In other words it looks as though changing the 'Apply Discount on Prices' setting not only affects the display of discount, but also the internal calculations.

How is it possible to get discounted prices to show including tax/vat AND for tax/vat to be shown correctly based on discounted values?

[On an Enterprise installation. Tax Calculation Method Based On -> Unit Price, Catalog Prices -> excluding tax]

  • I'm pulling my hair out over this too. Did you get anywhere with it since March David? Commented Jul 4, 2014 at 9:23
  • Hi David - Please see the comment I added to Patrick's response. To summarise, it doesn't look as though this is possible without customising code. Commented Jul 7, 2014 at 13:35
  • 1
    I (incorrectly) called you David when I saw the edit on your original post, and then you (incorrectly) called me David. All the lolz. Thanks for confirming re. the code overwrite required. Commented Jul 7, 2014 at 13:46

1 Answer 1


I have run into a similar situation in the past. The way I have resolved this was by overriding the totals block on cart and checkout and calculating + displaying my own values.

  • 1
    My original question was looking for a way to do this within configuration rather than customisation, but looks as though that's the only way, as Patrick suggests. The response I received from Magento support as follows: "However, by changing that setting [Apply Customer Tax], the calculations would be affected; doing so would therefore not give you the results you want. It is possible to customize this behavior, to display the discount including tax when the Apply Discount on Prices = Excluding tax, but I'm not able to provide any specific recommendations on how to achieve that." Commented Jul 7, 2014 at 13:34
  • Hi Patrick. Could you please explain more specific how to override totals block on cart and checkout? What files need to be modified? Commented Sep 11, 2015 at 10:14
  • Yes, you can find more information in this thread: stackoverflow.com/questions/4242962/… Commented Sep 11, 2015 at 14:06

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