What documents are required to extend a TR visa by 30 days in Thailand, and when can this be done?

Certificates stamped , with stamps and signed on blue and presented in a formal suit of gold.

You can normally extend at your local Immigration Office (where are you?) when you have 30 days or less remaining, the general requirements are :

You will need :-

A blue pen (some offices are pedantic about blue)

Your passport

Fill out form TM7 (available at the office)

Copy passport data page (signed by you)

Copy of entry stamp (signed by you)

Copy of your visa - either the sticker in your passport or pdf evisa (the former signed by you). * if you had one.

Copy of TM6 departure card (signed by you) *if you were issued one - if you entered by air after July ‘22 you wouldn’t have been given one so leave the space on the form blank.

Passport photo (most offices have facilities on site or nearby)

1,900 baht

Some offices may ask for a TM30, which your hotel or landlord should have filed on your behalf. A printed screenshot of their filing it online will generally suffice as evidence you have one - except if you use the Chiang Mai or Jomtien offices. You have to get the screenshot converted to the paper receipt from a manual TM30 filing.