- Taxes may be classified in a number of ways. One common distinction is between personal, or direct, taxes on specific individuals, like income, payroll or inheritance taxes, and 'in rem', or indirect, taxes on commodities, like purchase taxes. Some taxes are 'ad valorem', where the rate of tax is a proportion of the selling price, like most sales taxes, and others per unit, where there is a fixed amount per unit of the taxed item, like excise duties on tobacco and alcohol. Taxes on commodities may also be classified according as they are general taxes, like retail sales tax or value-added tax, or selective commodity taxes, like excise taxes and import duties. Factor taxes are taxes on factors of production, like labour or capital, and include property taxes.