What are the insurance requirements and documents needed for an OA visa extension in Chiang Mai?

To extend your OA visa in Chiang Mai, your insurance must cover at least 40,000 THB for outpatient and 400,000 THB for inpatient treatment. You'll need to provide two sets of documents: one for your local immigration office and one to be sent to Bangkok. The documents include proof of insurance coverage, an updated bankbook, and bank letters demonstrating you meet the financial requirements.