We'd need to know more about how you've set up your system, before we can tell you how to set up such a calculation.
Please tell us more about what you have set up.
I'm not sure what country you are in because a Value Added Tax varies from country to country. At present, I don't think U.S. has one, do they?
Anyway, let us assume that the VAT is 10%. To create price less VAT, it would be: price - price * .10 because it was marked up from manufacturer by 10%, marked up by retailer again and then the purchaser pays the additonal.
Only you knows where you fall in that category and what the rate should be. And it would vary depending up whether EU or non-eu contries so you may need a tax table for countries and the manufacturer markup on your product table - from which to pull the rate but I hope that gives you the math required if you know the VAT total to deduct.
I already have a billing program in which I make an invoice, fill in as follows.
artikle price * VAT * (19% VAT) = Prise including VAT
so I finally see in the bottom line excluding VAT than VAT, and the total price. Nice thats cool it works fine but
what I want is that i can set the total price including VAT , and that the calculation returns with the amount Ecluding VAT. i hope that i explain it richt , writhing in english is not my daily job
The reason I so want to this . is that it's easier for serval costumers.
contain some customers want to know the cost including VAT, so when I make the invoice I always count it back, what i want is, to let the program do this calculation, VAT in the Netherlands is 19%
So my calculation should give you that (except use .19 instead of .10. Have you tried it or am I still missing what you want?