Regulations Governing the pre-entry Customs Declaration of Import/Export Goods Article 7-1

In the event where the imported goods are approved by the Customs to be carried through pipes instead of transport means,the duty-payer shall make a pre-declaration with the Customs a month before the importation along with the supporting documents of the estimated quantity of the aforementioned import ,while an import manifest can be exempted.Where the goods referred to in the preceding paragraph have been released upon payment of import taxes and duties or deposits,the duty-payer shall summit the invoices and other supporting documents within the period announced by the Ministry of Finance,for the Customs to collect the unpaid taxes or to refund the deposits based on the quantity of the imported goods.
中文原文 進出口貨物預行報關處理準則第7-1條
經海關核准以非運輸工具載運而以管線輸入之進口貨物,納稅義務人應於貨物進口前一個月內檢附次月預估進口量之報關文件向海關預行報關,並免申報進口艙單。
前項貨物經繳納進口稅費或保證金放行後,納稅義務人應於財政部公告之期間內補具發票及其他證明文件供海關查核,並依實際進口數量辦理補稅或退還保證金手續。

English translation for reference only; the Chinese text prevails. Not legal advice.