What are the time frames for 90-day reporting at Immigration in Thailand and is there an online reporting option?

You can report your 90-day residency at the Immigration office in person from 15 days before to 7 days after your due date. The due date is included in this range. Online reporting is available from 15 days before your due date up until the date itself. You can also send your report via mail (EMS), but it must be stamped at least 15 days before the due date. The online reporting link is https://tm47.immigration.go.th/.