I think you misunderstand how personal income is taxed in Thailand. Take a look at what the Revenue Department has to say about this: https://www.rd.go.th/english/6045.html
I quote: "A resident of Thailand is liable to pay tax on income from sources in Thailand as well as on the portion of income from foreign sources brought into Thailand" (resident = stay >180 days per calendar year).
If the "income from foreign sources", which should include income from a foreign company, is not "brought into Thailand", it should not count towards taxable income, if I understand this correctly.
Do you have a different interpretation which would make income from a foreign company with no clients in Thailand fully taxable and how would you explain that?
I quote: "A resident of Thailand is liable to pay tax on income from sources in Thailand as well as on the portion of income from foreign sources brought into Thailand" (resident = stay >180 days per calendar year).
If the "income from foreign sources", which should include income from a foreign company, is not "brought into Thailand", it should not count towards taxable income, if I understand this correctly.
Do you have a different interpretation which would make income from a foreign company with no clients in Thailand fully taxable and how would you explain that?