Zoning in Kingdom of Thailand
The Board of Investment (BOI) has taken decentralization as a prime scheme to promote investments. Therefore, the board is giving companies who invest in less developed areas special tax and non-tax incentives. To be eligible for special incentives, the board has separated the the provinces of the Kingdom of Thailand into 4 groups which resemble similar development stages measured by earnings and primary facilities:
Zone 1: Bangkok, Nakhon Pathom, Nonthaburi, Pathoum Thani, Samut Prakan, and Samut Sakhon
Zone 2: Ang Thong, Ayutthaya, Chachoengsao, Chon Buri, Kanchanaburi, Nakorn Nayok, Ratchaburi, Samut Songkhram, Saraburi, Supanburi, Phuket and Rayong.
Zone 3: Krabi, Kamphaeng Phet, Khon Kaen, Chanthaburi, Chai Nat, Chumphon, Chiang Rai, Chiang Mai, Trang, Trat, Tak, Nakhon Ratchsima, Nakhon Si Thammarat, Nakhon Sawan, Prachuab Khiri Khan, Prachin Buri, Phangnga, Phattalug, Pichit, Phitsanulok, Phetchaburi, Phetchabun, Mukdahan, Mae Hong Son, Ranong, Lop Buri, Lamphang, Lamphun, Loei, Songkhla, Sa Kaew, Sing Buri, Sukhothai, Surat Thani, Uttaradit, and Uthai Thani.
Zone 4: Kalasin, Nakhon Phanom, Narathiwat, Nan, Buri Ram, Pattani, Phayao, Phrae, Maha Sarakham, Yasothon, Yala, Roi Et, Si Sa Ket, Sakhon Nakhon, Satun, Nong Bua Lamphu, Chaiyaphum, Nong Khai, Ubon Ratchatani, Udon Thani and Amnatcharoen.
The zones are shown in the below map: