Belgian and Luxembourgish passport holders can enter Thailand without visa for up to 30 days.
If you are travelling with a passport that requires a visa to enter Thailand, you have to request a transit visa.
Please consult for more information https://www.thaiembassy.be/wp-content/uploads/2021/09/VOA.pdf .
https://www.thaiembassy.be/2021/09/21/general-information-about-thai-visa/?lang=en and https://www.thaiembassy.be/visa/?lang=en.
Case 1 ( international flight transit):
If your transit flight does not require leaving the transit zone or passing the Immigration Checkpoint, and your luggage is checked through, THAILAND PASS AND INSURANCE ARE NO LONGER REQUIRED
Please be noted that these following documents are required:
– Thailand Pass QR code and medical insurance are not required.
The transit/transfer time shall not exceed 24 hours.

Case 2 ( international flight transit) :
If your transit flight requires leaving the transit zone or passing the Immigration Checkpoint(e.g. changing the airport), and your luggage is not checked through, THAILAND PASS IS REQUIRED
Please be noted that these following documents are required
– a proof of complete approved vaccination ( certificates of all doses). No PCR test will be required upon arrival.
– An insurance covering covid19 treatments worth at least 10,000 USD for the entire period of stay ( despite being less than 24 hours)
– Unvaccinated travellers are not eligible for this condition.
Case 3 ( Domestic transit) :
If your transit flight requires leaving the transit zone or passing the Immigration Checkpoint(e.g. changing the airport), and your luggage is not checked through, THAILAND PASS IS REQUIRED
Please be noted that these following documents are required
– a proof of complete approved vaccination ( certificates of all doses). No PCR test will be required upon arrival.
– An insurance covering covid19 treatments worth at least 10,000 USD for the entire period of stay ( despite being less than 24 hours)
– Unvaccinated travellers who choose to enter with a pre-departure negative PCR test are eligible for this condition. Those unvaccinated who undertake a quarantine are not eligible for this unless they take a seal-route flight to their destination and be subject to quarantine at their destination.