The Implementation Regulation for Leave of Prisoners Article 11

Prisoners shall bear their own cost required during leave periods.When a prisoner participates in public-interest service, no remuneration shall be collected. Necessary cost may be paid by the Prison or relevant authority (institution) or organization.
中文原文 受刑人外出實施辦法第11條
受刑人外出期間所需費用,應自行負擔。
受刑人參與公益服務,不得收取任何報酬,其必要費用得由監獄或相關機關(構)、團體負擔。

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