Seems like a dumb question, but a friend (not an expert) told me it is impossible. They said you would have to plan ahead and get a multiple re-entry.

Some people may not know in advance how many times they will travel and so only get one at a time(or even if less than 2 planned re-entries would be cheaper). The friend said that if a traveler with a single re-entry used it, and then planned to exit the country again, the traveler could not get a second single re-entry, but would have to re-apply for a new visa from outside Thailand, and start the whole process again. Is this right?

That is nonsense. You can get as many single re-entry permits as you want.

Lots of people get more than one because of unplanned trips or they don't plan on making enough trips to justify the cost of a multiple re-entry permit.

No, your friend is not correct.

However, you can only have one Re-Entry Permit in your passport at a time. If you buy a Single Re-Entry Permit you must use it (or have it canceled) before buying another.

Edited September 2, 201411 yr by mahjongguy

Having a valid unused re-entry permit and wanting to get another one?

Collecting two or three valid re-entries "on stock"? No, thats not possible.

But that was not the question of the poster!

If you have used your single re-entry you can get another one during within the limits of your extension of stay.

1000 Baht for a single, 3800 for a multi.

So its all about planning/expectation (frequent travellers better get a multi, saves money AND time [for application]).

The statements of the thread starter are definitely wrong, full stop.

Edited September 2, 201411 yr by KhunBENQ

"But that was not the question of the poster!"

Obviously. So, my comments about only one permit at a time were offered as a possible explanation for how such a silly idea originated.

Absolute rubbish. Whomever told you this nonsense clearly knows nothing about immigration in Thailand.