Labor Pension Act Article 17

For those who voluntarily contribute to the labor pension in accordance with Article 7, Paragraph 2, their employers or self-employed operators shall file with the Bureau of Labor Insurance to commence or terminate the contribution, and shall deduct, collect and make the contribution on a monthly basis.Those who voluntarily contribute to the labor pension referred to in the preceding paragraph shall contribute from the filing date of voluntary contribution to the filing date of termination.
中文原文 勞工退休金條例第17條
依第七條第二項自願提繳退休金者,由雇主或自營作業者向勞保局辦理開始或停止提繳手續,並按月扣、收繳提繳數額。
前項自願提繳退休金者,自申報自願提繳之日起至申報停止提繳之當日止提繳退休金。

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