Apparently it's $50,000 or equivalent.
Depends also on what , who, and Banks involved.
Registration for outward remittance
Because banks are quite tightly regulated in Thailand, many will require you to first register for their outward remittance service. Foreigners are asked for the source of income documents; Thais need supporting documents specifying the purpose of remittance.
The registration is typically done in one of their branches or, in some cases, online. But recently, some banks have stopped asking for this altogether for transfers in selected currencies. Once registered, you can send money abroad from their application or website at any time without having to go to the bank.
Read here...
Money Management