Children under 14 technically do need visas, however, they are not fined or banned if they overstay, although they do receive an overstay stamp in their passport.

And grateful I do my Extensions in Bangkok not Chiang Mai!

I'll be hanging on to my original tightly!

Chiang Mai seems to be a law unto itself. If I were the OP, I'd try taking it higher up for another decision. I wonder if they know it has to be done in the UK and not at the British Embassy in Bangkok. Shame she deleted her thread.

Ah. I'm in a similar position as I have an Extension based on work, with my wife and child piggy-backing on it as my dependents. Getting our UK Marriage certificate legalised and certified was a pain as it can only be done in the UK and then by the Thai Embassy in London, costs £30 and £10 for the Thai Embassy abd takes around 3 weeks. My Extension is due for renewal in November and I had NOT anticipated having to go through the process every year! After all the legalisation is just to confirm it's a legal certificate and as I have the original, surely once is enough! Hopefully this is just one rogue office....

My kid only has a UK passport (his mum is Lao) and he had a non O visa for Thailand and is now attached to my Extension. Kids do need visas although they are not fined or banned if they overstay. They do however get an overstay stamp in their passport.

Thai people can hold 2 passports.

@Robert ******

' advice is spot on.

You show the check-in staff the UK passport aswell.

Doing it by mail is easiest.

What about people who have a yearly Extension of Stay/Work permit (and re-entry permit)?