I'm a US citizen who recently arrived and had the usual 30 day transit visa stamped into my passport. It is highly likely that I will be accepting a post with a large Thai firm in the very near future. In the event that they are not up to speed on how to assist in processing work permits and Non-B visas, what do I need to know?

Is it possible to get the Non-B issued / changed from the transit visa up at Chaeng Wattana? Or will I need to exit Thailand and hit up a neighboring embassy / consulate to do the paperwork for me?

Thanks in advance!

Are you sure its a transit visa and not a visa waiver ? A transit visa is normally used by aircrews/marine crews etc

Think you would need at least 21 days remaining on your visa waiver to pull it off in Thailand, travelling to surrounding country to get a Non-imm B this will work out more practical.

If the company concerned are not up to speed on arranging WP's maybe better they take on a legal company to do it for them, could save pain for you later on..

You can apply for a work permit while in Thailand on a visa-exempt entry. Then with the receipt for the work permit application (form WP.3) and paperwork from the company you can go to a Thai consulate in a neighbouring country to get a non-B visa. After entering Thailand on the non-B visa you can pick up the work permit when it is ready.