What are the process of changing student arc (degree student) to working visa?
Your employer first need to get your work permit.
Then you may need to get a resident visa for white collar workers. You may or may not need to do this out of taiwan.
And you modify the reason of your ARC or get a new ARC with a new visa.
For more details, you may ask to NIA and BOCA, or check their homepage.
To change from a student Visa to a Work Visa requires for the company to apply for a Work Permit. Once that work permit is received you may then apply for your ARC. The type of student visa you have is important, if you are for example a graduating student from a Taiwanese institute of higher education, you may be Able to apply for an extension of your ARC to seek for employment opportunities. If you are on a short term residence visa for the study of Chinese at a language institute you may need to leave the country and enter the country on a visitor visa and start your application for a work permit.