Since 31 Oct 2019, foreigners applying for a Non O-A visa will be required to purchase health insurance during staying in Thailand.
Requirements
According to the official immigration website, the requirements for health insurance are below.
Applicants are required to have 40,000 baht outpatient coverage and 400,000 baht inpatient coverage.
Health insurance for Non O-A visa in Thailand since 31 Oct 2019
Only Non O-A visa is required to purchase health insurance
I called Chiang Mai immigration and spoke to the officer on 7 April 2020, he confirmed the new requirement will apply to Non O-A visas ONLY. Health insurance is not required for foreigners who apply for an extension of stay based on retirement.
Where I can buy the health insurance
According to the official immigration website, you can buy health insurance from longstay.tgia.org.
Immigration Call Center
If you have any questions, you can call 1178 or the immigration in your city.