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 entered by air 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
Most offices 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.
They add on the days so there is no downside to going early. Most offices allow 30 days prior but Jomtien, Koh Samui and Koh Phangan you have to wait until your final week.
That depends whether you are talking about an actual visa or just getting a free visa exempt stamp on arrival.
If you qualify for visa exempt then you just leave and you’ll get a new one on your next entry.
If you need a tourist visa to enter then you can get a re-entry permit before you leave and that will keep your “allowed to stay” date alive for when you return.