[henrikschroder]

The full value, since you bring it into existence as a farmer.

If you buy cabbages from a farmer and make cabbage soup, you are taxed on the value addition that soup making results in.

[psykovsky]

What about if you buy the soup and only put $1 more on it's price and sell it? What value did you add? Your profit, the one where you are already taxed? You still have to add VAT... Call it VAT or sales tax, it's a tax on the poor and should be killed with fire.