Ad varolem means 'relating to value.' Ad varolem usually accompanies other terms to create a value-related expression.
Ad varolem duties, for example, are fixed percentage duties imposed on imported commodities. The calculation of ad varolem duties are based on the price or the value of the commodity in question.
Ad varolem taxes are taxes that are calculated on the basis of value. Sales taxes and property taxes are the most common examples of ad varolem taxes.