I've been going to chaeng watana every 90 days to extend my ED visa & do a 90-day report. Unfortunately, the 2 dates (for the visa extension & the 90-day report) do not coincide. Question: if I end up being a few days late for the 90-day report, will I be penalized?

If you are making a 90 day report more than 7 days after the due date you will be subject to a fine of 2000Bht.

You can file your 90-day report 15 days before or 7 days after it is due.

It'll only be a few days late, so should work out. Thanks for the info!