The others already said it. This has nothing to do with Thailand! It's about the US, for example.
If you stay 180+ days in Thailand, 15% US tax on dividends paid by US companies.
If you stay 179 days in Thailand, even if you have an apartment there, and you travel the world for the rest of the year, 30% US tax on dividends paid by US companies.
This has nothing to do with Thai immigration or what they enforce. You are not allowed to claim the lower US (!!!) tax rate if Thailand doesn't see you as a tax resident.
If you lie to︀ the IRS and say you are Thai tax resident (i.e. that you spent 180+ days︁ in Thailand when you haven't), then that is a crime under US law. Period.
You can also tell IBKR you live in a country with an even lower rate, IBKR︂ won't check that (or it would be easy to fool them), but it would be︃ just as illegal.
My question was about if there is a way to be considered︄ tax resident in Thailand even if you spend less than 180 days in the country.︅
For example, many countries also count short absences. So if you spend 3 weeks in︆ Thailand and then 1 week out of the country, in many countries, they would count︇ this as 4 weeks in the country.
But apparently Thailand doesn't.