We know that it is possible to change a Tourist Visa to a Non-Immigrant "B" Visa at Immigration. But how about the case you're changing your Tourist Visa, first entry to a Non-Immigrant "B" Visa? If they don't invalidate your Tourist Visa - can you still use the second entry??

As an explanation why I would like to do it: I changed my Tourist Visa at the Immigration office due to employment purposes. However, I am still on probation in my job. So, if I were to lose my job it would be more beneficial for me to "recycle" the (second entry of the) Tourist Visa. (Non "B" is valid until late May, while the second entry of the Tourist Visa would allow me to stay in Thailand about six weeks longer.)

Anyone has experience with this scenario??

If your tourist visa is not stamped used and has one entry remaining you could leave the country and return using that during the period the visa is valid (and receive the normal days/extension) that it allows. Your b visa was used when issued and permitted stay will end on your departure.

If your tourist visa is not stamped used and has one entry remaining you could leave the country and return using that during the period the visa is valid (and receive the normal days/extension) that it allows. Your b visa was used when issued and permitted stay will end on your departure.

Cheers, lopburi for the prompt reply. Confirms what I thought.