I do not see any problem with this new law. Paying tax to Thailand for stays over 180 days is not the same as double taxation. To avoid any mistakes with the documents (Thai language) I chose to use a lawyer. (cost me 7 000 thb.)
She arranged a tax card and bankstatements. She sent all the necessary documents for me to the authorities.
In return 10 days later I received 2 documents.
1) "Income Tax Payment Certificate" R.O.21 and 2) "Certificate of Residence" R.O.22.
Next, I paid my tax to Thailand. And sent R.O.21 & R.O.22 to the tax authorities in my home country.
Which then registered my new information. Long story short, I got back the difference between paid taxes in Thailand and my home country about 6 months later.
The long processing time is my only point of complaint!! (I ended up with approx + THB 161.000.)