All travelers must register for a Certificate of Entry (COE) issued by Royal Thai Embassy.
All travelers must make a reservation at a Alternative State Quarantine (ASQ), at their own expense.
Foreign travelers must have an insurance to cover medical expenses in Thailand with a coverage cost of at least USD 100,000.
Travelers must have a Certificate of Entry (COE) issued by Royal Thai Embassy and a Fit to Fly health certificate issued at most 72 hours prior to departure.
All travelers who have received COEs are required to download and register via the ThailandPlus Application.
Children under the age of 2 are exempt from presenting a COVID-19 test.
Travelers with proof of recovery from the virus within the last 90 days prior to boarding. Proof of a recent positive viral test and a letter from your healthcare provider or a public health official stating that you were cleared to travel.
More info at the CDC site
Travelers who did not get tested, are advised to stay home and self-quarantine for 10 days after travel.