There are lots of good pages on how to extend a tourist visa in Thailand, which I will link to below.  This post is meant to add a few things and update a few things. A single entry tourst visa is good for 60 days, which can then be extended another 30 days for 1,900 baht, for a total of 90 days.  You can also get double or triple entry tourist visas, which means you get 3 entries with the visa, and if played perfectly, will give you 3 x 90 days which is roughly 9 months.

Chiang Mai Immigration

In early February, 2013, I was traveling around northern Thailand and I had to extend my visa, so I headed to the Chiang Mai immigration office. I used this page as a guide:
http://www.gotpassport.org/2010/10/22/easy-as-pie-extending-a-tourist-visa-at-chiang-mai-immigration-office/

The guide outlines the location and basic process.  I ended up showing up about 1 hour after it opened, and when the taxi dropped me off, there were few signs of where to go, and people everywhere.  After finding the visa extension area (a small 30’x30′ room), I asked around where I could get the visa form and a queue number.  I found the form, but I couldn’t find the queue number, so I just went to the front counter (even though there was a massive queue), and I asked for a number.  They briefly looked at my papers and handed me a #.  I then went to get copies of things (in a building about 25 meters away).  There was a massive queue for Filipinions (I think), but then a separate area for farangs, which was empty.  I found it pretty weird that they were helping farangs right away, but all these other people were waiting.  I also got a few passport photos there. Note: make copies and get passport photos before you go to the immigration office!

I then filled out the info, and waited.  I ended up waiting until 1pm (4 hours) before I got called.  Once called, I handed the guy my stuff and paid, and he said nothing.  He just took my stuff, looked at it, then passed it back to someone else and helped the next person.  After about 3 minutes waiting there, I asked him what the situation was and he said sit down and wait.  So I sat down and talked to a guy that had been waiting for around 2.5 hours since he handed them his passport/papers. I waited about 1 hour before getting called.

At the end of the day, it took me 5 hours of chaos to get my visa extended.  When they handed my passport back to me, they forgot to include change, so I had to interupt someone and tell them.  The whole process was very inefficient.  They were writing in notebooks instead of using a computer, there was no organization, the room was far too small for the number of people there, and there was no communication from anyone.  They gave no announcement of where to wait, how long to wait, or anything.  It couldn’t have been a worse process.

Tips:

1) You can download the Visa Extension form ahead of time here. Definitely do this.
2) Make copies of your passport, deparature card, entry stamp, and tourist visa page (if applicable) ahead of time.  Make 2 copies of each to be safe.  Also make a copy of the completed application form, just in case they ask for it (which they may).
3) Have a couple passport photos ready – you don’t want to be looking for a place to get one.  You can get them there, but you never know how long the queue will be.
4) Get there like 30 minutes before it opens.  I imagine being the first 10 people would safe you lots of time.
5) If you can, make a trip to the Bangkok immigration, it is far better, quicker, and easier (see below).

Bangkok Immigration

On May 8, 2013, I went to extend my tourist visa 30 days since my 60 day mark was coming up (Note: you can extend the visa anytime before the deadline – you don’t have to wait until the 60 days are up before extending.  The extension will start from when the tourst visa ends, not from when you go in.)

This page has the necessary info about immigration, up to date as of May 8, 2013, except 1 thing (see below):

How to extend your Thai visa in Bangkok

A few things to note:

1) The taxi from Mo Chit to the government building did cost 100 baht, but going from the government building to Mo Chit cost me 200 baht.  There was a bad traffic jam so the driver took me some other route.  Just be prepared in case this happens.
2) Not mentioned in the page above, you need a copy of the tourist visa page itself.
3) If you need to make copies of anything, go down 1 level, and it is about a 2 minute walk to a photo copy store.  The name is “Photo” copy or PhotoMax.  Ask someone downstairs where to make copies and they will know.
4) The government building is HUGE, one of the largest buildings I’ve ever seen.  Make sure you know where the immigration office is (see below) in case you get dropped off at a random entrance.

To add a bit more detail to the page above, here are some images I got from below which detail exactly where the immigration office is (source):

The government building - massive structure.

The government building – massive structure.

The location of the building exactly.

 

The location of the immigration office in the building.