When is the next 90-day report due after a retirement extension in Thailand?

This is the fool proof way to tell IF when you got a new extension your 90 day reporting was reset

Ask yourself

"When I got my new extension did I also get a new 90 day reporting receipt showing a new report date?"

If that answer is NO you did not get a new 90 day report receipt with a new reporting date then your 90 days WAS NOT "reset" 😮 😕 and you report at the time your current receipt tells you to

Whereas

If that answer is YES and you did get a new 90 day report receipt with a new reporting date then your 90 days WAS "reset" 😮 🙂 and you follow that date now for your next report

You should have received a receipt from immigration with your next port date on it.

90 days from your last report. The date is written on your last recipe from immigration.

Have a look in your passport, your next report will be stamped on the report receipt stapled inside your passport, which may be from your last 90 day report or if the IO gave you a new receipt when you did your extension, it will have the new date.

When you got your extension, did the immigration officer put a slip of paper in your passport that gave you a new 90-day report date that was 90 days from your extension? If not, then your next report is due 90 days after your previous report.

The clue is in the name. You report after spending 90 days inside the Kingdom. Not rocket science.

Last report or last entry into the country.