Bonded (underbonded) is the bonded system, which is an internationally accepted customs system.

It refers to a customs supervision business system in which goods imported by domestic enterprises approved by the customs are stored, processed, and assembled in designated places within the country under customs supervision, and the payment of various import taxes and fees is suspended. . The first is bonded warehouses, bonded zones, consignment sales and duty-free shops that serve international commodity trade; the second is incoming material processing, bonded factories, and bonded groups that serve processing and manufacturing.

Any items imported from abroad that are processed and exported to avoid future export tax rebate procedures are temporarily accounted for at the time of import and are exempted from paying customs duties first, which is called bonded.