Governor of Tak province orders closure of all 33 border checkpoints, crossings with Myanmar for at least a week because of COVID-19 outbreak (Xinhua, 19.10.2020). More categories of foreigners will be allowed into country from October (Xinhua, 29.09.2020). Government extends emergency rule against COVID-19 until 31 October (Xinhua, 28.09.2020).

At present you are only permitted to enter Thailand if they meet one of the following criteria: If you are on a diplomatic or consular mission, belong to an International Organisations, a representative of governments performing their duties in Thailand, or have permission from the Ministry of Foreign Affairs. This includes families. If you hold a work permit or have already been granted permission from the Thai government to work in Thailand or have the Certificate of Residence and a valid re-entry permit. This includes families. If you are the spouse, child or parent of a Thai national. If you are seeking medical treatment in Thailand (except treatment for COVID-19), or are caring for someone seeking medical treatment in Thailand. If you are an international student or the parent/guardian of an international student.
If you fall into one of these categories and have an urgent need to travel, you should contact the Royal Thai Embassy or Royal Thai Consulate in your country of departure at least 10 working days before your proposed date of travel. They will confirm the documents you need. When you get to Thailand, you will be subject to a 14-day state quarantine at a Thai government-designated facility at your own expense. If suspected of carrying COVID-19, you may be denied entry into the country.
Other categories include:
If you have been exempted by the Prime Minister or Permanent Secretary of Ministry of Foreign Affairs.
If you are a pilot-in-command and crew members with a fixed travel schedule.
If you are a carrier of necessary cargoes. You must leave the country immediately after your mission is completed.
If you hold a Foreigners work permit (WP3) and/or BOI certificate. You should contact your local Royal Thai Embassy or consulate for a permit to travel to Thailand. The Civil Aviation Authority of Thailand (CAAT) will arrange seats aboard repatriation flights for eligible passengers.
You should keep up to date with the latest information on the websites of the Civil Aviation Authority of Thailand, and the Ministry of Public Health.
If you have a Thai resident visa and normally live in Thailand but cannot return within the required year, you will be granted an extension to your compulsory return deadline. However, you are required to return to Thailand as soon as the situation improves.
On arrival: Certain categories of foreigners arriving in Thailand will be tested for COVID-19 on entry and again during quarantine.
Quarantine requirements: All travellers to Thailand, including all British nationals, are required to complete 14 days quarantine at a State Quarantine or Alternative State Quarantine (ASQ) facility.
Data Collection: You may be required to download the Thai Chana COVID-19 tracking app on arrival in Thailand.

As of 04:00 on Thursday 15 October, a ‘Declaration of a Serious Emergency Situation in Bangkok’ is in place. It will remain until further notice. Gatherings in Bangkok of five or more people are prohibited.
An emergency decree is currently in place until 31 October 2020. Domestic air travel options within Thailand are opening up but remain more limited than before. If you intend to leave Thailand and need to take a domestic flight to reach your international airport, you should check with your provider and plan accordingly. Bus, train and boat routes are opening up but may be subject to restrictions. Make sure that you can get to your international departure airport. Provincial authorities may enforce measures which are stricter or different to those in other areas, including closing borders or imposing internal travel restrictions.
Internal bus and train routes are opening up and travel between provinces is now permitted. However, travellers moving between provinces may be required by local authorities to undergo quarantine on arrival in a new province so you should check the requirements for your destination.
If you are taking an internal flight in Thailand, you may be asked to download an app or complete additional travel documentation. Some regional airports are temporarily closed – you should double-check before travelling. There may be road checkpoints in place across Thailand so you should carry a passport as proof of identification when in public. There have recently been instances where non-Thais have not been allowed to use transport between provinces or visit public sites, such as temples. A number of measures have been outlined stating, among other instructions, that you must not: enter high risk areas; hoard essential goods; attend public gatherings; propagate false information; Further measures may be introduced at any time. You should follow the advice of the Thai authorities. More info here.
A phased lifting of lockdown measures across Thailand is underway. Details of the measures may differ between different provinces. Measures may also change or even be reimposed at short notice in response to COVID-19 conditions. Provincial authorities may enforce measures which are stricter or different to those in other areas, including closing hotels and beaches. Check the details for the province where you are. Relevant penalties for breaches of regulations; Everyone should comply with the measures put in place in Thailand to limit the spread of coronavirus (COVID-19). There have been several cases of foreign nationals being arrested and fined or sentenced to jail for breaching restrictions. The Thai Department of Disease Control has linked the smoking of cigarettes to the impact of coronavirus. Smoking in public is banned and can result in a fine of up to 5,000 Baht. Electronic cigarettes are already illegal in Thailand and their use may incur further fines or imprisonment. Hotel and private rental accommodation is available throughout Thailand. Some services and facilities in hotels may not be available e.g. leisure facilities.
Most public places and services are now open with social distancing measures in place. Some entertainment venues such as pubs and clubs are still temporarily closed or operating with restrictions. Some provinces may impose stricter measures including lockdowns on certain premises. Most shops and malls etc now have processes in place to register customers on entry and exit.

Quarantine requirement at government designated site.
All travellers to Thailand are required to complete 14 days quarantine at a State Quarantine or Alternative State Quarantine (ASQ) facility.

COVID-19 negative certification required for entering the country.

A medical certificate indicating that you have tested negative for COVID-19 (RT-PCR test) within 72 hours before your departure.
If you are an international student or the parent/guardian of an international student. You will need a Certificate of Entry issued by the Royal Thai Embassy or the Royal Thai Consulate-General in your country of departure, a fit-to-fly health certificate , a medical certificate indicating that you have tested negative for COVID-19 (RT-PCR test) within 72 hours before your departure, proof of health insurance covering all medical expenditure, including for COVID-19, up to USD 100,000 minimum while in Thailand, and written confirmation that the quarantine facilities you intend to use on arrival in Thailand comply with official rules. When you get to Thailand, you will be subject to 14-day quarantine at your own expense, and you will be tested twice for COVID-19 during this time. If suspected of carrying COVID-19, you may be denied entry into the country.