Help with Coupons to discount off Tax included Ammount

Please help i need a fix for this urgently, this was done before but there was no reply on how to fix it.

I need for the coupon to discount on the Gross Ammount (subtotal & tax) amount before any shipping or other fees are applied!

Can I change some code somewhere so that the coupons will always take the value / percentage off the Sub Total inclusive of GST or TOTAL less shipping & other fees.

Currently I get:

Sub-Total:$46.43
Coupon:$-10.00
GST (15%):$5.46
Total:$41.89

I need it to work out like this:

Sub-Total: $46.43
GST (15%): $6.96
Coupon: $-10.00
Total: $43.39

Any Help would be really appreciated
I am using version 1.5.1.3

I need help with this as well. Did you find a solution?

Nope still waiting for some help on this and many other things. Let me know if you find a solution too thanks.

In extensions > order totals set the sort order to put the coupon last just before the total. It will deduct the discount from anything above it.

Hi. I need to do the same thing. Setting up the order total is not working for me:-( Have you found a solution yet? the coupon (both percentage and fixed amount is deducting from sub-total and only the amount deducting is without the tax. for example if i make a 100 % discount the amount opencart subtract is 84 but the full amount is 105 (including 25% tax). The same is if a make the discount fixed amount at 105, then opencart only subtract 84.

Can i be the first to say that what you want, may not actually be legal in your country, the tax applied is always based on the net total, i.e before tax. Which is why your coupon discounts the sub total before tax is applied.

It IS working for you both, what you dont get is how it should be applied.

If you add the discount after tax, then the amount of tax does not correctly relate to the sub total.

And finally, why in the hell would you want to pay more tax to your country on sales and take less for yourself? It doesnt make sense to anyone. Ill even prove it to you.

First and Correct method

Sub-Total:$46.43

46.43 - 10 discount = 36.43

36.43 * 3 / 20 = 5.46 (GST 15%)
total = 41.89

What you want

Sub-Total: $46.43
GST (15%): $6.96
Coupon: $-10.00
Total: $43.39

43.39 * 3 / 20 = 6.51
46.43 * 3 / 20 = 6.96

you just overcharged the customer tax of 0.45 all because you discounted the grand total, not the sub total.

The amount of tax you charge, is not for you, or anyone else to decide what is best, it is a goverment regulation that you must follow to the letter, infact you can get in serious trouble if your ever caught over charging tax.

I strongly advise you read up on your countries rules concerning tax and apply it correctly.

Changing the sort order works fine thanks.

maybe it is not the right way to do it, but in germany all major online shops deduct the coupon amount from the total, including vat.

to change the sort order works, if your coupon amount is less then the cart amount.
if the coupon is greater than the cart value, something weird is happening. the total amount gets deducted, but the vat still remains, so that the total in the end equals the amount of vat that was included.
which is not the way i suppose this should work!