Do I need a re-entry stamp when leaving Thailand during my free year on an OA visa?

THESE are the common found requirements for the re-entry permit

I believe you have the OA visa for retirement... obtained in your home country.

If you have bounced out and reentered prior to the end of the One year from the date of issue of the OA visa, you will be stamped in for a second year., With proof of the required health insurance policy.

During that second year, IF you want to leave Thailand and reenter Thailand, you MUST have a re-entry permit each time you leave. Buy it from the Thai Immigration office or at the airport BEFORE you LEAVE THAILAND.

I think we need to clarify that a bit.

You can only "bounce out and back" to get your free second year on an OA visa you buy from the thai consulate in your country before you come here AND you need a new year of the mandatory 100K USD health insurance to get it 🙂

Now to answer your question;

IF after you've bounced out and back and gotten that 'second year' entry on an OA visa and you need to leave the country you DO need to buy a re-entry permit BEFORE you exit (single re-entry permit 1000 baht, multiple re-entry permit 3800baht)

because that's what keeps your stamp "alive" and if you don't you'll cancel the stamp and lose the time