Regulations Governing Certified Public Accountants Acting as Income Tax Agents Article 7

A CPA shall join at least one CPAs Association before applying to register himself/herself as a tax agent and handle income tax related matters nationwide as mandated.A CPA who has registered as a tax agent before this article was amended and came into force on May 10, 2016 may handle tax related matters nationwide rather than within the jurisdiction of the province (city) where he/she registered.
中文原文 會計師代理所得稅事務辦法第7條
會計師至少應加入一省(市)會計師公會後,始得申請登記為稅務代理人於全國受託代理所得稅事務。
會計師於本條中華民國一百零五年五月十日修正施行前已登記為稅務代理人者,其受託代理所得稅事務不以原申請登錄之省(市)區域內為限。

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