[GNC] Invoice tax bug in GNUCash 4.13?

[Etienne]

Hello,

I noticed that when I enter a discount my tax amount is off.
It seems that GNUCash 4.13 calculates the tax on the item price and ignoring the discount amount.

I enter an invoice with:
quantity: 1
item price: 169.95 (sale price including taxes/VAT)
discount type: $
discount how: > (so the discount is after tax)
discount amount: 17.00
tax included: X
tax table: German VAT (19%)

I then get:
subtotal: 125.82
tax: 27.13

So they add up to the discounted price of 152.95.
However the correct subtotal should be: 128.53 and VAT/tax should be: 24.42

I tried different settings, like <, = and no tax included.

Also, when I enter the price excluding vat (so 142,82) then the tax is still off when applying a discount.
Only when adding the discount to the price and skip the discount column, then it calculates VAT fine.

Is this a bug or intended use?

Thanks.