Tax imposed on customer affects demand or supply curve? I have a example of supply and demand. If there is a regulation that requires customers to pay additional tax when they purchase cigarettes, would supply or demand curve shift? I know that tax/subsidies is one of supply's non-price determinants, however, it is only applicable to producers. I doubt that this example is concerned with demand curve. Nevertheless, tax is not one of demand non-price determinants. Thanks!
In partial equilibrium, demand shifts down, with the (vertical) distance between the pre-tax and post-tax curve being exactly the height of the tax. 

pre-tax curve: $q=f(p)$

post-tax curve: $q=f(p+t)$