An excise, or excise tax, is any duty on manufactured goods that is normally levied at the moment of manufacture for internal consumption rather than at sale. Excises are often associated with customs duties, which are levied on pre-existing goods when they cross a designated border in a specific direction; customs are levied on goods that become taxable items at the border, while excise is levied on goods that came into existence inland.

An excise is considered an indirect tax, meaning that the producer or seller who pays the levy to the government is expected to try to recover their loss by raising the price paid by the eventual buyer of the goods. Excises are typically imposed in addition to an indirect tax such as a sales tax or value-added tax (VAT). Typically, an excise is distinguished from a sales tax or VAT in three ways:

1. an excise is typically a per unit tax, costing a specific amount for a volume or unit of the item purchased, whereas a sales tax or value-added tax is an ad valorem tax and proportional to the price of the goods,
2. an excise typically applies to a narrow range of products, and
3. an excise is typically heavier, accounting for a higher fraction of the retail price of the targeted products.

Typical examples of excise duties are taxes on gasoline and other fuels and taxes on tobacco and alcohol (sometimes referred to as sin tax).