To file a TM30 on a Saturday, it depends on the immigration office you are visiting. In Chiang Mai, the offices are open on weekends specifically for TM30 filings, allowing you to file or update it on both Saturday and Sunday. If the immigration office is closed due to holidays or weekends, you won't be penalized for filing it the following day.
If the immigration office you use is closed (holiday/weekend) and you go the very next day they are open you won't be fined for failure to file a TM30 on time.
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