Wrong calculation order

Tags: #<Tag:0x00007ff4a8f82b78>


I think you mean the discount for each item in invoice/quote. For invoices you must change following lines in application/modules/invoices/models/mdl_item_amounts.php :

$item_subtotal = $item->item_quantity * $item->item_price;
//$item_tax_total = $item_subtotal * ($item->item_tax_rate_percent / 100);
$item_discount_total = $item->item_discount_amount * $item->item_quantity;
$item_tax_total = ($item_subtotal - $item_discount_total) * ($item->item_tax_rate_percent / 100);
$item_total = $item_subtotal + $item_tax_total - $item_discount_total;

And the same way for quotes in application/modules/quotes/models/mdl_quote_item_amounts.php :

$item_subtotal = $item->item_quantity * $item_price;
// $item_tax_total = $item_subtotal * ($item->item_tax_rate_percent / 100);
$item_discount_total = $item->item_discount_amount * $item->item_quantity;
$item_tax_total = ($item_subtotal - $item_discount_total)* ($item->item_tax_rate_percent / 100);
$item_total = $item_subtotal + $item_tax_total - $item_discount_total;

Short solution:

  1. Delete/comment old line for $item_tax_total
  2. Calculate $item_discount_total first
  3. Substract $item_discount_total first from $item_subtotal and than calculate $item_tax_total

@Kovah May you patch this issue in next version?

Tax on discounts for products
InvoicePlane v1.4.3 released

Hi, I’ve tried all posted solutions and haven’t been able to solve the discount order issue. I need the discount to be calculated before the tax is applied, but no matter what I change it won’t have an effect. It even shows after the tax when creating new quotes.

Have anyone found a working solution to this. Also is this an error or is how it’s intended in the first place, because if it is, it would be great to have a setting to use it one way or another.


Added an issue report for that.

closed #4