Sales tax is an ad valorem tax, rather than an excise tax. It’s based on value rather than measured amount. A gas tax is normally an excise tax, levied per gallon rather than per dollar soldFuel, alcohol and tobacco are the most common excise taxes and bring in the most revenue.The sale of Illegal drugs are often subject to excise taxes as well, mostly to provide additional charges and penalties on top of whatever can be enforced from the crime of illegal drug sales themselves.
An excise is an indirect tax, meaning that the producer or seller who pays the tax to the government is expected to try to recover the tax by raising the price paid by the buyer (that is, to shift or pass on the tax). Excises are typically imposed in addition to another indirect tax such as a sales tax or VAT. In common terminology (but not necessarily in law) an excise is distinguished from a sales tax or VAT in three ways: (i) an excise typically applies to a narrower range of products; (ii) an excise is typically heavier, accounting for higher fractions (sometimes half or more) of the retail prices of the targeted products; and (iii) an excise is typically specific (so much per unit of measure; e.g. so many cents per gallon), whereas a sales tax or VAT is ad valorem, i.e. proportional to value (a percentage of the price in the case of a sales tax, or of value added in the case of a VAT).