Do I need to do my 90 Day Reporting if I leave Thailand before the due date?

This question comes up a LOT

This is how it really works

IF you are on a visa/extension that requires 90 day reporting and you stay in thailand 90 continious days you are obligated to report. <- That's the rule, there's no wiggle room

In person you can report from 2 weeks before your due date until 1 week after without a fine

This does NOT mean if you're leaving during that '1 week after the due date' that it's a 'grace period' and you don't have to report. It is NOT, that 3 weeks just happens to be the "window of opportunity" to report in person is all

Online you can report from 2 weeks before your due date until 1 week before the due date.

Now, what will happen when you leave the country without doing a 90 day report (that we've already covered you're obligated to do)?

When you stamp out nothing will happen because the officers at passport control don't care if you ever filed a 90 day report or not as it's not their job.

When you stamp back in to thailand your next 90 day report will be due 89 days from the date you stamped in (the day you stamp in counts as day one no matter what time you enter).

Will immigrations catch the fact that you didn't file your previous 90 day report and actually stamped out of the country after it was due?

As a rule, they don't catch it, but I have seen them catch it, make you pay the 2000baht failure to file on time fine, then let you file the new 90 day report

I will leave it to you to decide your course of action. I'm not even gonna let commenting open on this post, I'm posting the rules as they're written and what I have seen that's it