@Craig *****
Whew, good. You can get ONE 90 day extension of stay based on STV. ASK your local immigration office what their requirements are. If you are using Bangkok immigration, you would submit the same documents are you did when you applied for the STV. I'm attaching an e-mail from Bangkok Immigration about what they require.
>then extend again just before the 30th of September?
Probably not. Most immigration offices require no less then 45 days remaining on the existing "admitted to/ Extension of stay granted until..." stamp before you can apply for another extension of stay. Some require no less then 30 days. Bangkok requires 3 days.
>s it correct that covid extensions aren't possible for an stv?
I *HEARD* reports of the immigration offices allowing people to get a 60 day extension of stay based on unable to travel due to COVID-19 on the STV. You will need either a letter from the embassy saying the borders are closed, OR a cancelled airline ticket (FROM THE AIRLINE COMPANY) with a re-scheduled flight, OR other supporting documents why you can not depart from Thailand. The requirements for this extension are extremely high to meet.