Once the visa is issued you never need to show the money again unless you want to stay more than 6 months and apply for an in country extension. Your visa will be valid for 5 years from date of issue with unlimited entries of 180-days
The 180-day tax residency has always been a thing but only the last
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years has everybody been panicking about it. Being tax resident does not mean you have a tax liability. Only if you bring untaxed money onshore, earn money in Thailand or have investments in Thailand do you require a TIN and file a tax return, otherwise just enjoy your holiday in Thailand. As a tourist you are not even allowed a bank account so stop worrying about tax liability.
My first time at Suvarnabhumi was all done in 90 seconds. The IO was very impressed with my laminated A6 e-visa. She kept saying very easy to scan and showed it off to her colleague :D
The 180-day tax residency rule has always been in place, but only this last
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years have ppl started to worry about it. You only need a TIN and file a tax return if you bring untaxed money onshore, work in Thailand or have money invested in Thailand. Otherwise enjoy you holiday/retirement