A different degree of facilitation is provided to the licensees of Zero-GST warehouses (ZGW) according to the standards of controls put in place by the licensees. ZGWs are classified into Type I, Type II and Type III licenses according to the robustness of controls put in place.

Companies with effective inventory controls will be allowed to upgrade their licence type to a Type II or Type III licence, if they have good internal controls and a computerized inventory system. A Type I or Type II licensee who wishes to upgrade to Type II or Type III licence, as appropriate, will have to apply to Singapore Customs in writing.