Can you be more specific? Do you want to say why you need to declare at home and abroad? Because normal domestic to domestic transportation does not need to be declared, except for the bonded area.

Goods sent abroad from China need to be declared, and vice versa. On the one hand, as a national gate, directly under the authority needs to count import and export information to facilitate the big data management of goods. The state can regulate and manage the import and export of goods according to the situation. On the one hand, the payment of foreign exchange needs to be based on the import and export declaration form, otherwise you can't catch the suspicion you said. The most important import and export declaration form is an important basis for enterprises to pay customs value-added tax and enjoy tax refund. Taxation is the foundation of a country's finance.