Based on my own research (someone feel free to correct me if wrong), IBKR is available for Thai residents but IBKR is not considered a "Thai brokerage", because it's not regulated by the Thai SEC. Your account is with either the HK or Singaporean IBKR legal entity. So technically, profit in your IBKR account is not taxable in Thailand. However, you may need to fund the account from a Thai bank account and cash out to a Thai bank account, so those monies would potentially be taxable when funding and cashing out as they would be Thai-remitted at those points. It seems most brokerages generally prefer you to fund and cash out from/to an account in the same country where the account is registered to. I've read stories on Reddit where an account holder cashed out to a bank account in a foreign country and their account was subsequently closed by IBKR (seems they do allow it but your account might be reviewed and closed after the fact). I'm wondering if you can open another IBKR account in Thailand and do an internal transfer from your old IBKR account. In theory you would only then pay Thai tax when you cash out through your Thai bank account.