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https://asq.in.th/thailand-pass
Pending Final Approval
The MFA / Ministry of Foreign Affairs has recently announced that the Certificate of Entry (COE) will be replaced with the "Thailand Pass" system starting November 1st, 2021.
The "Thailand Pass" online registration system will exist on https://thailandpass.go.th, and should be accessible by November 1st, 2021.
Recent News Articles around "Thailand Pass"
The new Thailand Pass system will be for everyone except for those who will be traveling as part of group arrivals (by sea), and Alternative Hospital Quarantine (AHQ) stays will. They will have to use the existing COE system until otherwise specified.
Required Information for Thailand Pass
Passport Information
Vaccination Certificate
Covid-19 Health Insurance Coverage
SHA+/AQ Hotel Booking
It appears that prepaid COVID-19 PCR tests may no longer be required (recently mentioned in the Phuket Sandbox reduced requirements).
At the moment it is very hard to draw any final conclusions on the ease of the process, and who exactly will be able to enter "quarantine free". The chart released by the MFA did not seem to cover this newly announced entry method.