People on Ko Phangan ๐ด extending their stay after entering Thailand on a visa exemption - Please note that your hotel (or landlord, I guess) needs to complete an online document called TM.30 and upload a scan of your passport, and then they send you a document that you need to print, before you can apply for an extension for your visa. (Btw My hotel had a lot of difficulty getting the government app and the passport scan to work properly. The hotel knows how to use the app, but says it doesn't work well.)
I had a wasted trip to immigration as I did not know about this part of the procedure. This would have been a bigger issue if I'd left my visa extension until the last minute.
I don't know if this hotel document is a requirement in some other parts of Thailand too.
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Edit: for people who are saying this is a standard procedure, I've never been asked for a document from my hotel when extending in Ko Samui. It had not occured to me that different immigration offices might have different requirements. Also, not all hotels ask to see your passport at check in.
P.s. apparently there is a room at the immigration office in Ko Phangan where you can have your photo taken. However, there is not a printer where you can print the TM 30. You need to do that independently elsewhere.
Best wishes ๐