I know this has been done to death but I can't find the answer so please help.
I have come to Issan for one night and am staying in a local hotel who has taken a copy of my passport.Assuming they will do a TM30 as is required of them, am I required to do one on my return to Bangkok? I seem to remember it wasn't required by Bangkok Immigration.
TLDR : Answer Summary
A TM30 is generally not required when returning to Bangkok after traveling within Thailand, as confirmed by commenters. However, procedures may vary by immigration office, with some requiring it to be filed within 24 hours upon arrival. Failing to file a TM30 could result in a fine.