I am on a non-imm O extension. I know to get a reentry stamp on the way out. When I return do I need to go to my local immigration office, or does my 90 days automatically reset from my arrival?
TLDR : Answer Summary
When returning to Thailand on a non-immigrant O extension, your 90-day reporting starts again upon reentry. You need to calculate the days yourself for the first 90-day report after returning. Additionally, it's required to report your address at the immigration office within 24 hours of your return and file a Tm30 form.