What are the requirements for renewing an O-A visa in Thailand and is health insurance still mandatory?

You are going to need to provide more information:

What office are you using?

Is this your first extension of your OA?

When does your current visa/extension expire?

you also have to meet the financial requirements for a 1-year extension of stay permit out of an O/A Visa. These are either 800,000 THB on a bank account in your sole name, seasoned for 2 months on the date of your application, or proof of a monthly income of a minimum of 65,000 THB. Seeing you are from the UK, the later option would require a full year bank statement of incoming from abroad 65,000 every month for the recent 12 months (because your embassy does not issue a letter of income proof any more). That and the mandatory Thai Health Insurance showing cover for the whole duration of the year you will receive the extension for, and you will be fine to go (plus passport, TM30 receipt, 90-days report receipt, Bank book, etc)

I did my extension in January. It was business as usual, except I was able to make an appointment which minimised my time at CW.

I have placed TOPIC

Non OA Extension

On your post..

Click on it and posts re OA extensions will pop up to read.

Which immigration office are you using?

Yes...health insurance is still needed for the extension of the O-A visa inside Thailand.

It must be from one of the approved insurers.

Health insurance*

A certificate of health insurance issued by Thai insurance companies covering the entire period of stay in Thailand containing the details of coverage as follows:

In-house patients of not less than THB400,000/policy year, as for out-patients, not less than THB40,000/policy year.

Please check for more information regarding participating Thai insurance companies.