The Immigration department announced that foreigners on current visas must complete their 90 day report between August 1 – 31, when they extended the visa amnesty at the end of July.
The visa amnesty finishes in less than a month. What happens to people without a current visa after September 26?
Really, you have 3 options. Leave the country before the amnesty finishes. Or find a way to extend your visa. If you are unable to leave the country, because of flight issues returning to your country, or some other medical or urgent reason, you should contact your Embassy or Consulate ASAP. They may be able to provide you with a letter recommending an extension of your stay.
https://thethaiger.com/hot-news/expats/90-day-immigration-reporting-must-be-done-by-the-end-of-today-august-31