UPDATE: As of right now the 14 quarantine has been canceled (never actually started).
foreigners and Thais returning from Japan, South Korea, Germany, China, Taiwan, France, Singapore, Italy and Iran, Macau and Hong Kong are subject to a 14 day home quarantine REGARDLESS of symptoms, effective immediately.
Foreigners without a permanent residence (tourists) MUST show immigration PROOF of where they will be self quarantined at for 14 days or they will be refused entry.