What should I do with my NON B Visa after my work permit expires if I'm leaving Thailand soon?

When your NON B Visa expires alongside your work permit, you must address the situation with immigration. If you're leaving Thailand within a week after your work permit's expiration, you should go to the immigration office to cancel your NON B Visa, accompanied by your work permit cancellation paperwork. If you plan to leave permanently, simply exiting the country is also an option. Notably, you can apply for a 7-day extension for 1900 baht to legally stay until your departure.