Is it possible please, to use a re-entry permit after entering on a Single entry 90 day O visa based on retirement?

Yes,  you can purchase a re-entry permit from your local immigration office. Or you can get one at the airport on your way out.

 

A single re-entry permit costs 1000 baht, or at the airport there is an additional 200 baht surcharge for photo and filling in of paperwork, so 1200 baht.

 

A re-entry permit does not add any time to your entry stamp. The date on your entry stamp remains the same and time keeps ticking down while out of Thailand.  So you would still need to be back before the stamp you received upon entry expires so that you can apply for your extension.

OP, correct advice above. 

You use a TM8 form. 

It requires a photo. 

The optional service charge (200b) at airport includes immigration providing photo, fill out form etc

Ask for details of process at airport as BKK slightly different to DMK

Thank you. 

Can the re-entry permit be purchased at any Immigration office in the country or only where the tm30 is registered?  Reason being, want to visit the islands of Satun shortly and may  but not sure yet fancy a nip over to the Malaysian islands as well.  TIA

18 minutes ago, Almudena said:

Can the re-entry permit be purchased at any Immigration office in the country or only where the tm30 is registered?  Reason being, want to visit the islands of Satun shortly and may  but not sure yet fancy a nip over to the Malaysian islands as well.  TIA

anywhere, and most airports

Any office, but be aware that it only keeps your current permission to stay alive, you don't get new days.

I once entered on two days left on my extension on re-entry permit, got two day stamp.

Next day to immigration and renewed my marriage extension