Can I enter Thailand on a 90-day flight ticket with a 30-day tourist visa and extend it locally?

I rented an onward flight ticket to Singapore for 12 euros for 29 days after my arrival as I was going visa exempt, although intending to extend by 30 days. At Etihad check-in the staff member did remark that I had no return ticket, so I just told her I was going to SG on 15th December, and she was satisfied without my having to show her anything. Immigration, however, didn't ask to see anything, and in my experience of flying to Thailand twice a year for 17 years they never have.

One of the most asked questions here.

You need to have a flight ticket out of Thailand within the amount of days that your initial entry allows, regardless that you can get an extension in country.

In theory immigration can deny you entry if you don’t but they rarely ever would, because they know you can get an extension.

Almost always the hang up will be when you try to board your plane. Many airlines will not allow you to board without an onward ticket within the number of days.

Some will let you. Many won’t. You probably don’t want to be the one scrambling to buy an onward ticket at the check in desk. Best option is a changeable ticket, and just change the date when you’re here.

Alternatively you can Google “onward flight ticket” and you’ll find a plethora of companies willing to sell you one for around $10.

This is without a doubt the most asked and answered question this month.