Problem with quantity pricing and VAT

[gswd88]

Hi all,
I have been having problems with VM2 and attempting to do the following:
Basically all I want to do is have quantity tier prices with the VAT working properly for EX VAT prices. At the moment, whichever way I try to set it up I always end up with the following problem: After adding a product to the basket with sufficient quantity, the discount is applied, however the VAT is always calculated on the non-discounted base price regardless of what quantity tier I am in. The following example shows my problem.

Some tape has a base price of £0.60 each. When 222 or more are purchased the base price becomes £0.58 each.  The product tax is set to a UK VAT rule which is of type 'VAT Tax', with a rate of the standard UK VAT of 20%.

When the product is added to the basket with qty of 222 or more the following is shown:
Price column shows as £0.6, qty: 222, VAT: £26.64, discount: £4.44 and in the total, a value of £159.84 is crossed out and a value is £155.40 is underneath.

The amount of VAT shown is calculating on the original price, not the discounted price: (0.60*222*0.2) = 26.64 rather than what it should be which would be (0.58*222*0.2) = 25.75. As a result of this the discount amount is also incorrect.

I have tried many different ways of setting this up - changing the TAX to VAT TAX and vice versa, using the Istraxx quantity discount plugin with a price rule of 'discount before tax', using the inbuilt 'add new price' feature of the new version of VM.  - Whatever I try I always end up with the same problem.

Am I doing something fundamentally wrong in my tax setup or are there other issues here?

Regards