Enforcement Rules of the Estate and Gift Tax Act Article 20

In the event that a decedent has left properties behind upon death, regardless of the taxable amount, the taxpayer shall fill out the estate tax declaration form and file the tax declaration with the competent taxation authority accordingly. Where the tax base calculation involves a deduction, exemption or exclusion, relevant documents of proof shall be attached.For the purpose of gift tax declaration, the taxpayer shall fill out the gift tax declaration form and submit along with it all relevant documents of proof.
中文原文 遺產及贈與稅法施行細則第20條
被繼承人死亡時遺有財產者,不論有無應納稅額,納稅義務人均應填具遺產稅申報書向主管稽徵機關據實申報。
其有依本法規定之減免扣除或不計入遺產總額者,應檢同有關證明文件一併報明。
贈與稅納稅義務人辦理贈與稅申報時,應填具贈與稅申報書,檢同有關證明文件,據實申報。

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