Tax Residency is not based on where your income is. Yes he will owe Geeman taxes on income paid into Germany. Just like a Brit would have a tax liability on income paid there ie for rental properties but could be Tax Resident elsewhere ie here in Thailand. They are not mutually exclusive. You can own tax in more than one tax jurisdiction. The clue is in the term "Tax Residency".
Yes apply in Vietbam and wait for Visa. There have been cases though where someone applied in LA. Came to Thailand on Visa Exempt while Visa was processing. Visa was approved to they flew out and back in to activate the DTV.
I did not suggest any special rules for DTV. Have you been drinking too much Chang Beers today. Bye BTW not all visas have to be applied for outside the country. "O", "B" in some cases. Certain BOI visas. You do not know as much as the Chang is telling you
Anonymous participant Then you would have to move your tax residency from Germany to Thailand. No idea how it works in Germany but when I left the UK it was just a matter of filling in a form for UK tax authorities and registering in the next country. As moved through countries I just registered in the next ie Belgium then Singapore and now Thailand.
There is nothing official yet from The Royal Thai Police Immigration Department on whether a 90 day report is required on a DTV Visa. Until that is promulgated by them anything else is speculation and guesswork.