about the new tax law for foreigners

It is important to note that in Thailand, individuals who are considered tax residents (i.e., those who have resided in Thailand for 180 days or more) are eligible to receive a tax credit for the amount of tax already paid overseas. This is made possible through the Double Taxation Treaty that Thailand has entered into with other countries. As such, double taxation does not apply to tax residents in Thailand.

Only the income received overseas and/or in Thailand is subject to personal income tax. Transferred money is not subject to it but you have to declare the source and the purpose of transfer for it being able to be transferred back.