half way through my retirement visa and want to get a multi entry visa as i will be in and out of Thailand for the next year. My question is, would the multi entry visa run for a year or would it finish when my retirement visa finishes. thx

It finishes with your current extension. When you get a new extension you must get a new re-entry permit (either at the same time or before you leave the Kingdom).  I always get a multi re-entry permit at the same time as my extension. On a few occasions I've only used the permit three times (so losing money against using single permits) but, to me, the convenience outweighs the possible loss.  

It will only run until the expiry date of the retirement extension. 

It is based on your Permission to Stay. 

Edited January 5, 20206 yr by jacko45k
typo

You are probably on an extension of the permission to stay of your (already expired) Non Imm O or OA Visa granted you, so you need a re-entry permit to keep that permission to stay alive when exiting and re-entering Thailand.

You can buy such a re-entry permit at any local IO or at the departure desks of the major thai international airports.  A single-entry re-entry permit costs 1.000 THB, and a multiple re-entry permit costs 3.800 THB.

Obviously you would need to buy that re-entry permit before exiting Thailand.

 

Edited January 5, 20206 yr by Peter Denis