What is the 90-day report, exactly?
It is your regular address notification to Thai Immigration — effectively a check-in. You tell them where you are living and they log it. That is the whole substance of it. You can file in person at your local Immigration office, online in certain cases, or by post.
The official name is TM.47, or Tor Mor 47. Tor Mor is the Thai abbreviation for the Immigration Bureau, and the 47 is simply the form number in their filing system. Almost nobody uses the formal name.
Most, though not all, Thai long-stay visa holders have to file it. It sounds simple enough — until you try to work out when the next one is due.
Why does every trip out of Thailand reset your clock?
Every time you leave Thailand and re-enter, the 90-day clock restarts from your re-entry date. This is the rule that causes the most confusion, because a report you had diarised can move months into the future without any notification from anyone.
Say your next report is due 1 April. You leave on 2 March and re-enter on 18 March. The report is no longer due 1 April — it shifts to 16 June, exactly 90 days from re-entry.
Leave again on 6 May and re-enter on 12 May, and that June date shifts again, to 10 August. Every re-entry restarts it.
There is a wrinkle. The first report after any entry or re-entry usually has to be filed in person. After that, if you stay put, later reports can often be filed online. A trip resets both the timing and the in-person requirement.
Why is your next report counted from the due date, not the filing date?
If you do not leave Thailand, your next report is due 90 days from the previous report's DUE date — not from the day you actually filed it. Filing early inside the 15-day window does not pull your next deadline forward, and assuming it does is a common error.
Say your last report was due 1 April and you filed it on 24 March, inside the early filing window Immigration allows. It counts as on time.
Your next report is still due 90 days from 1 April, which is 30 June. Not 90 days from 24 March, which would be 22 June.
People assume the clock starts when they filed. It does not. It starts from the due date of the previous report — unless they left Thailand, in which case the whole thing resets.
What happens if you miss one?
A late filing can carry a fine of up to 2,000 baht. That is not ruinous, but missing enough of them creates longer-term friction with Immigration. There are no reminders: no email, no SMS, no app notification. Tracking the date is entirely your responsibility.
If you are on a long-stay visa, this is something you deal with for as long as you live here. Not once or twice — permanently.
Long-term expats who have been here a decade still forget when the next one falls. The rules are just complicated enough that even people who understand them mistime it.