There are different types of Non-B visas, for employment and for conducting business.
In general, is it possible to apply for a work permit with a 1-year multiple entry (non-B) visa (assuming one fulfills the requirements for a work permit), or does it necessarily have to be a three month single entry visa?
TLDR : Answer Summary
Yes, it is possible to apply for a work permit with a 1-year multiple entry Non-B visa, provided that the applicant meets the necessary requirements for the work permit. However, some embassies typically issue a 3-month single entry Non-B visa if the applicant does not already have a valid work permit, requiring the applicant to extend it later while in Thailand. In specific cases, individuals may need to first obtain a 90-day single entry Non-B visa, secure their work permit, and then apply for the 1-year multiple entry.