Proving I'm leaving Thailand...

The problem isnt with Immigration in Thailand BUT the airline when you check in. You could either get a visa before leaving, a cheap flight out within 30 days or Plan C-- wait till you get to the airport and be ready to get online to book a flight out if asked for proof.
A hostel booking in another country definitely wont cut the mustard.

Thanks for the info westwood.

Hmm. I'll call my airline and see what they say...

Otherwise, there must be pre-bookable transport out of thailand. The consulate seems to suggest there is: "Foreigners entering Thailand... are required.... to have proof of onward travel (confirmed air, train, bus or boat tickets)"

As westwood points out, Thai immigration is not, necessarily, your problem. The airlines is. And, you can't go by what someone on the phone tells you. It's up to the check in staff.

You can book a cheap Air Asia, Nok or Bangkok Airways flight, to one of your other SEA destinations, online.

And regardless of what the Consulate says, the airlines will in all probability want an onward flight.

Hmm. I'll call my airline and see what they say...

Waste of time. As pointed out above, the person you speak to on the phone will not be the one to check you in, and that's where the hurdle is. Time and time again we've been told the stories have been different between phone call and check in.

You need to follow the wise advice already given - you cannot make it up as you go along simply by saying "but there must be a way...etc etc"

The consulate is right, but what they don't tell you is that they don't police very well their own rules. It's the airline who faces the big penalties for carrying pax who then cannot get entry, so it's the airlines who can be super-cautious in the first place, and not board you.

Since it's very difficult to obtain boat tickets out of Thailand, or train and bus tickets, it usually comes down to having an airline ticket onward within 30 days of arrival. Or a Tourist Visa (TV) already obtained.

Do as Westwood tells you - get to the airport early and be prepared to go online to buy a one-way ticket on, say, AirAsia from Bangkok (DMK) to Phnom Penh (PNH). Look up fares now for your dates, so you know what price we're talking here. You may well breeze through check-in without being asked why you haven't got a visa. They may accept it when you say you'll be heading out of Thailand after only a week (or whatever). If so, no problem - there'll be no worries entering Thailand with visa-exempt stamp when you state on your landing card that you will be staying less than 30 days.

The ONLY alternative to this is to get a 60 day TV in your passport before you leave Ireland.

You could print up an itinerary mentioning dates and names of guest houses in Siem Reap, onward to VIetnam, whatever - it all could help. Chances are you will not have a problem boarding, but if you do then you must be prepared to play ball. Another poster will advise you to ask to sign a "disclaimer" form if they don't wish to board you. They may give you one, but they probably won't. At this point, if you're having a problem, you just do what check-in want - or you don't fly!

Good luck - thousands go through this every single day.............................

Here is what I have done over the last couple of weeks. If you have a return ticket why is the airline even asking the question? When you enter through BKK you fill out the arrivals card and they staple the departures card into your passport. No questions no answers. (29June) Fill out he departures card when you are ready to leave.
Flew AA FD606 to PNH on 2 July, filled out departure card, at DMK , no worries. Flew back on AA FD611 from REP on 8 July into DMK, again no dramas no tickets etc. I am off to CNX today on Nok DD8312 then to UTH and road hop across the border to Vientiane and then re-enter at Friendship Bridge. Again , I expect no problems.

So we are arriving on the 23rd of July, and return flight is on the 3rd of September.

@#6

If you have a return ticket why is the airline even asking the question?

Because OP's return ticket is way past the 30 days to qualify for visa-exempt arrival. All the examples you gave are fine because they are all short trips where the 30 days rule isn't applicable.

Going by the reports on this forum it strikes me that the only airlines ever asking this question are the ones that work in the ALTEA check-in system and cannot be bothered with a workaround. If you come across the word in your airline blurb, be prepared. Doesn't help you alot, just thinking out loud.

Yep...get a Tourist Visa...£25..£10..added for doing it on the day you show up at your nearest Thai Consulate..end of drama. The Arab based Carriers are hot on this forward ticketing. PS you have to show up in person now unless you post all the guff to London Consulate..they did not win prize from me for their social skills so I rolled into Liverpool..great as usual,but not local for you...take care.