I currently have a non b visa for teaching with 3 month validity. I plan to go home for a month in December and go back to Thailand in January. I will get a 1 year extension before i leave. My question is if I get a multiple re-entry permit before the 3 months expire, will that be valid for the 1 year extension as well or would I need a new re-entry permit for the extra year segment of the visa?
TLDR : Answer Summary
If you obtain a multiple re-entry permit before your non-b visa's 3 month validity expires, it will not cover your one-year extension. Once the extension is stamped in your passport, you must apply for a new re-entry permit.