Land Tax Act Article 21

For any land approved by the municipality or county (city) government to be subject to vacant lot tax, a vacant lot tax of two to five times the basic land value tax payable for the land will be levied.
中文原文 土地稅法第21條
凡經直轄市或縣(市)政府核定應徵空地稅之土地,按該宗土地應納地價稅基本稅額加徵二至五倍之空地稅。

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