Requirements from 01 February 2022 for round 2 of test and Go Thailand:

• COVID-19 Travel Insurance is mandatory and the insurance policy coverage must be of no less than US$ 50,000
• Certificate of COVID-19 Vaccination/Recovery, check the vaccination requirements as some vaccines are 1 dose some are 2.
• Travelers below the age of18 years are not required to present proof of vaccination if traveling with a parent or legal guardian, that said this is Thailand so perhaps take a copy if you have it just in case.
• Hotel Confirmation Letter for Day 1. The letter has to confirm the pre-paid accommodation, airport transfer and RT-PCR test and must be issued by an AQ or SHA Plus+ hotel
• Hotel Confirmation Letter for Day 5 or 6, this hotel may be different from the Day 1 Hotel. The letter has to confirm the pre-paid accommodation and RT-PCR test and issued by an AQ or SHA Plus+ hotel. You can book 2 different hotels for the accommodation on Day 1 and Day 5. On both Day 1 and Day 5, you must stay within the hotel room awaiting the RT-PCR test result. Failure to do so could lead to arrest and deportation.

The difference between Test & Go and Sandbox Programmes

With the Test and Go, you’re free to go anywhere  in Thailand after you have passed your 1st test. You have to stay in a SHA Plus+ hotel with a partner hospital on Day 5 while you await the result of the 2nd test. In practical terms, you can have your 1st test in Bangkok and your second test in Pattaya as long as you stay and wait in an SHA Plus+ hotel on your fifth night to complete your second test.

What is the point of the Sandbox when Test & Go will now be open to people from all countries? The sand box can be used for travelers whom may not have been vaccinated or be eligible for the Test and Go Thailand option, further should the test and go be further cancelled or postponed then the sandbox option remains.

I have already applied for a Thailand Pass for the Sandbox. Can I switch to Test & Go? Yes you can, but you have to apply for a new Thailand Pass when registration re-opens on 1st February. Some people may get the QR Code quickly but it can take up to 7 days. Remember doing this could result in delays and expenses so check your costs and travel plans before you change your plans.

I have a home in Thailand, do I have to book a SHA Plus+ hotel for the 2nd test?
Yes, there are absolutely no exceptions to this. The 2nd hotel can be anywhere, but it must have a partner hospital and you must wait in the room for the results like you did for the first test. failing to do so usually means arrest and you could be deported too.

If you booked your Thai Pass prior to the December 22nd deadline it is not clear at this point if you have to book a second day 5 hotel and test if in doubt contact the Thai Pass registration offices prior to travel.

Source : https://www.tatnews.org/2022/01/thailand-reopening-exemption-from-quarantine-test-go/