I've looked around a little, and it seems that "compound" and "stacked" taxes are synonyms, and they just mean multiple taxes at the federal and local level that are "compounded" or "stacked" to make up the final tax rate.
I'm guessing the closest thing you have is VAT.
Using Google, I can't find a direct translation anywhere.
Is VAT in Italy only a federal tax, or can the regions add on a tax to it?
I think VAT is something different, Tim. I don't think it could be defined a compound tax.
The only thing I can think of is something like imposte composte - as in there are some documents where taxes must be applied in a certain order so as to produce the final "result". But there's no thing like federal/local taxes over here (I don't think so, anyway)... As far as I know, we've got a system in which the State collects the taxes from all Regions and then redistribute them according to some criteria.
There's only one type of taxes - at the "central" level (which is a thorny issue in the political arena, but that's beside the point )... over here, I think the term tasse (or imposte) composte can only mean multiple kind of taxes (i.e. on income, on properties, etc.) can be combined in a single "calculation".
Hope this helps... I'm not really an expert in the matter, take what's above with reservations