@Brian *******

, Check your passport to see what you are on now.

If you are still on the entry stamp from the visa (90-days for Non-O for over 50, or up-to-365-days for Non-OA) with an actual visa sticker or eVisa PDF

-> The same as OP, you cannot transfer your visa. Carry both passports until the visa itself expires.

If you have already applied for a 1-year extension at the local immigration office (read the stamp)

-> Different from OP's case, you have to transfer the stamps to your new passport.

A visa issued by a Thai embassy or consulate cannot be transferred to a new passport. You have to bring both passports until your visa expires to enter Thailand on your visa.

That depends on the embassy/consulate you applied through. For example, 20 days are way too short for one embassy such as Paris, but way too long for some other embassies.

Did you check their visa processing policy on their website?

And,

Check the spam box to check if you have emails requesting additional documents.

Ankara says “IT TAKE 5-10 BUSINESS DAYS AFTER SUBMITTING THE COMPLETE APPLICATION OR RE-SUBMITTING THE REVERTED APPLICATIONS) FOR THE APPROVAL OF THE VISA.” on website. They also have holiday calendar on their website. Check them and see if you are still in the processing time or not.

Contact them directly if both are negative.

@Curt *******

, check Tod’s latest comment on this post

@Eve *******

, unfortunately, no.

So as I wrote, once he gets a new passport from home, bring both passports, enter on the new passport using the old one. Then go to the Phuket office to transfer stamps when he returns to Thailand. And make sure that he is stamped in on his new passport correctly as his extension (with "Non-RE" as visa class on entry stamp, until November 3), before leaving the passport control when he enters Thailand.

@Fabrizia ******

, yep, he is definitely on an extension for studying in a formal school.

Actually, there is no Non-O for the reason of attending school. Also, no Non-O multiple entry (still valid) for reasons other than being a spouse to a Thai (there are a few very specific exceptions, though).

Now Doubtful your son has an actual multiple-entry Non-O visa. If he is studying at a real school, he could be on 1-year extension with a multiple re-entry permit. Or up to 3 months extension (incremental) if he is studying at a private school, such as a language school.

Check his current visa or stamp and make sure what he is on now, at least whether he has an entry stamp directly from a visa, or an extension (for whatever period).

He can enter Thailand being stamped on his new passport, using his current visa/extension on his old passport. But visa/extension cannot be transferred at entry point. He needs to go to the local office that issued his extension to transfer stamps once he is back to Thailand. Don't forget getting re-entry permit before leaving Thailand, and don't forget to bring his old passport back to Thailand.

Only at the immigration office that issued your current one-year extension. If yours was issued at Chaengwattana, you must go to the Chaengwattana office.