How long does it take for a 90-day report to be approved online in Thailand?

go back into the system, go to the check status tab, enter your information and see if the report is approved or not

I would say it depends on where you are located. It gets approved by the office you report to in your area. In Bangkok where I do mine online, the last time it took about 7 hours, it has taken a couple of days in the past also. You can go back to the site and put in the confirmation number you received or your passport information and check the status also, either pending, approved or not approved. It is also kind of a hit or miss it seems to whether you receive a approval email from my office in Bangkok. I did get an approval email the last time I did it, but I think that was a first for me and I have done it online maybe 7 or 8 times now online. So my answer to you is probably 6 hours to a couple of days if your office is utilizing the online reporting. Good luck.