Customs duty is an important part of national tax revenue, a chief source of Central fiscal revenue, and also a means of the contracting parties of the World Trade Organization to protect their domestic economies. Levying tax legally is one of the main tasks of the Customs.

(Ⅰ) The Definition
Customs duty is a kind of circulation tax levied on the goods and articles entering or leaving the customs territory by the Customs on behalf of the nation in conformity with the tariff policies formulated by the nation as well as the tax laws and the import and export tariffs promulgated and implemented by the nation.

Customs duty is a kind of national tax revenue, which is its most essential nature. The nation is the subject of taxation of Customs duty. Customs duty is collected from the taxpayers by the Customs on behalf of the nation. The object of taxation is the goods and articles entering or leaving the customs territory. The laws, the administrative rules and regulations formulated by the nation are the foundation of the Customs duty collection.

The importance of Customs duty is determined by its basic nature. Although the function of Customs duty is not entirely the same in different times of different countries, the basic function of it is the consistent embodiment of national sovereignty. The purpose of customs duty collection is to maintain sovereignty and promote the national economic construction.

Practically, the so-called "Import Duties and Taxes" in some international conventions and agreements differ with the concept of Import Customs Duties. "Import Duties and Taxes" include Import Customs Duties and other domestic taxes levied on the imported goods. After going through duty-levying procedure and approved by the customs, imported goods should be regarded as the domestic commodities and treated equally with home-made commodities, and therefore, should be levied domestic taxes likewise. Usually, domestic taxes are levied by the customs during import period, but they don't fall into the category of customs duties.

The Customs Law of the People's Republic of China prescribes that the Customs of China should levy taxes legally on the import and export goods and the articles entering or leaving its customs territory. Some international agreements limit the definition of customs duties to the tax levied according to the import and export tariffs. The definition excludes anti-dumping duties, anti-subsidy duties and retaliatory taxes, which are not listed in the tariffs.

As prescribed in the Customs Laws of the People's Republic of China, the consignee of the import goods, the consignor of the export goods and the owner of the articles entering or leaving the customs territory are the taxpayers of customs duties. Taxpayers of customs duties have the right to make inquiries about customs duties, to enjoy legal tax-reduction and tax-exemption, to require the customs to return the over-levied tax, to apply to the customs for an administrative reconsideration in conformity with the legal procedure or to file an administrative suit in the People's Court when objecting to the decision of customs on duty collection, At the same time, the taxpayers of customs duties have the obligation to accept legal supervision and control of the customs, to make truthful declaration to the customs about the condition of the import and export goods or articles entering or leaving the customs territory; to accept the audit of the customs, and to pay the amount of tax ratified by the customs within the time limit according to the law. The taxpayer should bear the corresponding legal responsibility for his behaviors violating the Customs Law.