you pay tax where you live - simple as that. And if you live in Thailand over 180 days, you're a tax resident of Thailand. Instead of contacting the ATO, try contacting the Thai Revenue Department and ask them. And if you're bringing money into the Kingdom not declaring tax in Thailand, they are talking about targeting foreigners who dont.
Not true - I'm Australian but Im not a tax resident of Aus and pay income tax in Thailand and have done so for years. And I should add, not having to ever deal with the ATO ever again is a blessing.
You can rent a house from anywhere from 5k through to 100k a month, but if you want something mid-tier nice, you can get a newer furnished house
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x2 in a nice estate with a pool and community facilities for around 25k first or second ring roads. After that, the cost is relative to what you want to eat - if you eat Western foods in restaurants all the time, the cost is more than eating a mix a Thai and foreign. 50-75k/month, all up for everything, would be comfortable.