Do you need to file a new TM30 every time you leave Thailand or just when traveling within the country?

The TM30 requirement primarily depends on the local immigration policies. Generally, you are only required to file a new TM30 when you leave Thailand and re-enter, not for travel within Thailand as long as you stay at the same place of residence. However, if you stay at a different hotel, that hotel must file a TM30 on your behalf. The obligation to file the TM30 falls on the host (like a landlord or hotel) rather than on the individual, unless the person owns the property. There may also be variability in how different immigration offices enforce these rules.