A transit visa is required when you wish to transit through Thailand to another country of destination or re-enter your own country. This type of visa allows you to enter the country up to four times and is valid for 90 days, with a maximum allowable stay of 30 days.
In addition to a 6-month valid passport, two passport-size photos and a printout of the completed online visa application form, you’ll need to provide proof of travel reservation and financial confirmation (in the form of a bank statement, income certificate, sponsorship letter indicating 10,000 baht per person and 20,000 baht per family).
In addition, you will need a cover for accommodation in Thailand (this can be a reservation of accommodation or letters of invitation from relatives or friends in Thailand) and a visa of a third country to which you are traveling.
Additional Notes: Transit visas are also available for athletes participating in sporting events (TS – S) and for pilots or captains driving vehicles to country ports or stations and crew members (TS – C).
For TS-S additional supporting documents include a certificate from the relevant authority confirming the applicant’s participation in the event, a letter of invitation from the organizer of the sporting event and proof of travel reservation.
For TS-C you need a certificate of employment confirming that you are a crew member.