Foreigners wanting to work in Thailand must have a work permit.
Getting a work permit is a lengthy and cumbersome process. It is not
practical
at
all for the visitor who wants to pick up a few extra baht to extend
their holiday.
The thought of a working holiday leads many foreigners to bypass the procedure. This is not a good idea.
There are unscrupulous people who offer training and equipment, then
"guarantee"
jobs
for
certain
skills
when their training is finished. Scuba diving is one example.
What they
usually
fail
to
divulge
is how difficult obtaining a legal work permit is. Some dive instructors
in Thailand dodge the Immigration Bureau for years while trying to
get a work permit.
If you are caught working illegally, you will be put in jail and/or fined up to 5,000 baht. This is as true for the foreigner who steps behind the bar to help the bar staff, as it is of the English teacher working at a language school with no work permit.
While arresting teachers is rare, it does happen.