Frequently asked questions related to Thailand Entry Requirements are listed here. The answer to your question might be already answered here. If it's not, place your question in the comment box below.
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What document needs to be filled if my nationality lets me enter Thailand with no visa?
All nationalities must fill and submit Thailand Immigration Card at the time of their arrival in Thailand. More information about how to fill this document can be found here: Thailand Arrival Card – How to Fill Arrival Card Form.
How much money I need to show at the time of the arrival?
If you are coming visa free or will be using a visa acquired in advance from Thai Embassy or Consulate, you might be asked to show that you have at least 20000 THB per person or 40000 THB per family in cash. It can be equivalent amount in any currency so you don't need to exchange your money in advance.
Visitors using Visa on Arrival need to show 10000 THB per person or 20000 THB per family.