When you apply for an extension, you will that extension until the earlier date of a specified period (such as 1 year, etc) or your passport validity. (There is no such thing as an "application for getting remaining days after passport renewal".)
If you are applying for a 1-year extension and want to get a full year, you need to have a passport valid for longer than 1 year from the extension starting date.
, That's what you need to check the exact embassy you are applying for your tourist visa. Some clearly say you need to show within 60 days, some say within 90 days is acceptable because of the extension.
Depends on your nationality, if you can apply for a 30-day tourism extension.
Check your entry stamp. IF your stamp shows "ผ.30", you can apply for 30 days extension. If you have another "isa-class" on your entry stamp (ผผ.30, ผผ.90, etc) for free entry, you are not eligible.
In case you can apply, you will go to IT Square Laksi Plaza temporary office, just next to Lak Si station of SRT Dark Red Line or MRT Pink Line.
There is no Immigration office near Impact Arena anymore as it had moved to IT Square Laksi.
You will go here.
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You can book online here
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Attached is general information for a 30-day extension for tourism purposes.
It totally depends on the organisation you are volunteering with whether you can apply for Non-O volunteering inside Thailand at the local immigration office or you have to apply for one at the Thai Embassy/consulate in another country. Experience with a different organisation is irrelevant to your case. You have to talk with your organisation. They are the ones and only who can answer your question.
, the first 1-year extension from the initial Non-O visa has to be applied for the same reason as the initial visa. You can change the reason for the second 1-year extension or later.
Please make your own post if you want to ask further.