Passport
You have to possess a valid passport for traveling to Bangkok. In addition, the passport should have a validity period of not less than 6 months. You cannot enter Thailand with a passport that has less than 6 months validity. In case your passport has expired, ensure that you renew it at the earliest. Make sure that the passport is undamaged and has all the pages intact.
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Excepting certain cases, tourists visiting Thailand must have a tourist visa, which has a validity of either 3 or 6 months. In case, you wish to extend your stay, you must file an application for permission at the Office of Immigration Bureau in Bangkok. It is advisable that you contact the nearest Thai Embassy or Consulate-General to find out where you should apply for a visa to Thailand before departure.
Identity Card
One of the most important documents that form a mandatory part of your travel documents is a card that serves as an authentic proof of your identity. More often than not, you might be required to validate your identity at the airport. Failure to do the same might lead to severe legal repercussions. Therefore, it is important that you carry a photo identity document, issued by a competent authority of the municipality, state, or country in which you reside, for e.g. Driver's License.