Thosaporn Serirak, the government spokesman, said that the overhaul is to ensure fairness in income distribution and plug taxation loopholes.
Under the new structure, individual income is subjected to seven tax brackets, from 5 at present.
In the first bracket for taxable income upto Bt300,000, those with taxable income lower than Bt150,000 would be waived.
The spokesman said that the new structure will cut the government revenue in the 2013 fiscal year by Bt25 billion.