Hi, i am not sure, but maybe there is error in calculating VAT in invoice. See my invoice with discount.
VAT is calculated as VAT from products + vat from discount. Right variant is VAT products - VAT discount, this is wrong. All other numbers are OK.
Virtuemart shows it right, your vm invoice in irder preview and order detail shows it OK too. Maybe bug?

Hi,
I couldn't replicate the problem - see attached screenshot.
Do you use the latest version of VM Invoice 2.0.27? What versions of Joomla and VirtueMart do you use?

yes, vminvoice 2.0.27, joomla 2.5.14, vm 2.0.22

in VM there is all ok, send me screen of your config of Invoice Items Configuration. On my screen the line coupon has no minus before value. In yours screen there is, we use % discount coupons...

if i choose option Show Total Tax Line - without coupon discount, system shows on invoice Vat from items, if i choose yes - deduct coupon discount - value of vat is vat from items + vat form discount, right should be vat - vat discount, maybe because of missing minus before discount value...

It's strange that you don't have the coupon discount displayed as positive value. Here is my configuration:

we have the same config and vat coupon is calculated different, i tried to make new coupon code, make test order, same result.

Could you tell me where can i set this in php code direct? i do not need to make this settings via admin, so i will heck it in the code for creating invoice

after update of VM to 2.0.22c problem is still there, let me know, where to edit this directly in the code