The collection of the taxes is usually the duty of the regular fiscal officers of the general administration, but industrial and commercial receipts are frequently collected by special boards in charge of them, who turn the money over to the Treasury. Assessment and collection are so closely connected that they can be studied together. In the collection of customs duties there are two things for the officials to care for. (1) They must look out for the arrival of all the taxable commodities and prevent smuggling.(2) They must ascertain the value ofthe goods if the taxes are ad valorem, and the number of pieces if specific. The invoices, supported by the usual certificates, oaths, etc., are of the nature of a declaration by the owner, or importer. They are then subjected to the scrutiny of official appraisers, whose knowledge of the nature and value of the goods is very accurate. The tax is then paid to the collector at the place of importation or when it reaches the recipient in the interior, but before it is delivered to him. In case the goods are to be admitted into the interior of the country, or of the customs district, before the tax is paid, as is the case when the person to whom the goods are sent resides in the interior, the package is sealed up, or "bonded," and the seals can only be broken by an authorised collector after the payment of the tax. In countries where there are no general tax collectors in the interior, this method is not feasible, and the goods are held in the custom-house on the boundary until the tax is paid. With a few exceptions this is the practice of the United States. But in Germany, where there are regular fiscal officers of the central government in almost every hamlet, goods are regularly shipped to the consignee, and the tax paid in the interior.

In the case of excises, the factories, breweries, fields, and other places where the taxed goods are produced are subject to regular inspections and are more or less under the constant supervision of the officials. The tax is collected directly from the producer or by the sale of stamps and licenses.