We recently upgraded to the latest version of Zencart (v1.3.9h) but have since discovered a problem in the final check out VAT calculation.

Originally, we had the following set up for the Total Order Module:

Sub-Total ot_subtotal: 200
Shipping ot_shipping: 250
Tax ot_tax: 300
Total ot_total: 999

This worked fine in the previous version, but since upgrading we note that the Tax/VAT (300) only includes VAT for the goods 'Sub-Total' (200) and NOT Shipping (250), so the resulting 'Total Due' is wrong.

I finally decided to change the Total Order Module settings to:

Shipping ot_shipping: 100
Sub-Total ot_subtotal: 200
Tax ot_tax: 300
Total ot_total: 999

This seemed to fix the problem, but several days later we discover we have the same problem!

The reason I say it 'seemed to fix the problem' is that I now note that if I personally test the system, then MY order total includes postage VAT and is therefore correct. However, if ANY OTHER person logs in, then VAT is not included in the postage.

All postage options in the 'Shipping Modules' are set to 'Tax Class: Taxable Goods'.

For example, I tried to simulate a problem that occurred today:

Customer order:
Goods Total: R152.01
Postage (Speed Service): R65.79
Sub-Total: R173.29
VAT: R21.28
Total: R239.08

My own 'test' order:
Goods Total: R152.01
Postage (Speed Service): R75.00
Sub-Total: R173.29
VAT: R30.49
Total: R248.29

And if I set up another new 'test' account, then that customer's order also fails to add the VAT to the postage. This new 'test' account, like 99% of all other registered customers, is set up as a residing in the country, and therefore pays VAT.

Anyone have any idea why the VAT isn't being included in the postage and WHY is my own account (and ONLY my account) calculating VAT in the postage?