Health insurance has been made mandatory for foreigners aged 50 years and above seeking long-term stay in Thailand. The insurance policy must offer up to 40,000 baht coverage for outpatient treatment and up to 400,000 baht for inpatient treatment.

This is one of the measures the government has introduced to ease the financial
burden placed on state hospitals by foreigners, many of whom have not paid for treatment. The Thai government has already approved the new rule, the new rule applies to both new applicants for the non-immigrant visa (O-A), which offers a stay of up to one year, and those wishing to renew their visa. Each renewal is valid for one year.

Foreigners can buy valid health insurance from longstay.tgia.org or if they wish to
use health insurance that they bought overseas, they must ensure that the coverage
amount is no less than what is required by the rule. Foreigners who cannot buy health insurance because their health risks are considered too high, might have higher deposits in bank accounts so as to make sure that they have enough to live in Thailand.

Further information can be obtained from this link:
https://longstay.tgia.org/Home/Guideline?fbclid=IwAR3Bdv4NDvN94FcDHWGFIaM5
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