Basically 2 systems prevail for VAT purposes:
"Location based " where taxes are due (sales or purchases in the company's country) or exempted (exports), based on the location (Country) of your partner.
"product based" where VAT and applicable rates are depending from the product/service itself; this is the case for VAT.
How does OpenErp allows to setup these 2 configurations, which may co-exist for one company or group of companies?
you can somewhat have the two concepts by applying VAT to products and then use fiscal positions for partners. See question 7593/smart-fiscal-positions. Have not tried it. And it does not really solve my problem 23331/apply-partner-taxes-even-if-there-is-no-product-tax-set. There should be a way to have partner or location taxes independent of product taxes. Also, in Germany, VAT is based on location, not product. There are taxes that are genuine to products, think of luxury goods, tobacco, alcohol and the like. However, most of them also apply only to local sales, not exports.