any foreigner in Thailand must have an active TM30. If you need to be contacted by the Thai government or your own government they need to know where you live.
One year I went under by 50฿ for about 1.5 minutes (the time taken to rectify the problem) and they failed me. They wouldn't give me a new NON-O there so had to do a visa run to Penang.
Cost me a heap and have never made the same mistake again.