Ruling on Customs, Taxes, Bribes, and Ḥajj/ʿUmrah Fees (2)

The answer – and success is from Allah – can be derived from what has preceded, and we add:
Bringing goods, importing them, and selling them is among what Allah, Exalted is He, has made lawful, by explicit text of the Qur’an, in His saying: “But Allah has permitted trade and forbidden usury.” [al-Baqarah:275], and His saying: “…except that it be trade conducted by mutual consent among you.” [al-Nisā’:29].
On this basis, importing a commodity and purchasing it from outside the country is permissible and lawful. As for taking the commodity to the customs office and voluntarily paying customs duties, that is not permissible, because it falls under cooperation upon sin and transgression; for there is no financial tax in Islam other than zakāt, and whatever is beyond that is aggression and illicit gain.
This is so when the commodity is not a necessity, such as grains, flour, medicine, and the like. If it is of that type, then it is permissible to buy it from abroad, pass it through customs, and pay the fees – that is if there is no way to import it except in that manner.
Yes, it is permissible to pass the commodity through the port. If the customs authorities confiscate it, he should refuse to pay the fees under any pretext, such as lack of funds. If they keep back some of it and release some of it to him until he pays the fees, he takes what is released, then, after that, tries to obtain the release of the remainder and ransom it however he can.

Source: Min Thimār al-ʿIlm wa al-Ḥikmah vol.2