I believe you are confusing the "window of opportunity" when you can do an online report and when you can do a report in person. :/
You can file online from 15 days before your due date up until the actual due date.
You can file in person from 15 days before your due date up until 7 days AFTER the due date without a fine.
You do NOT file 90 day reports at Chaengwattana anymore. The 90 day reporting was moved to the Muang Thong Thani Immigration office in July.
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