The plan to tax SET traders has been around for 30 years, but it has always been waived by the government to support market development.
The move proposed by the Finance Ministry is expected to enable the government to generate 10 billion to 20 billion baht per year.
SET investors have to pay 0.1% of share sales before expense deduction.
However, investors will have to pay only 0.055% of share sales after including local tax during the first year once the draft royal decree issued under the revenue code comes into effect.
More details about financial transaction tax will be revealed later, the government said.
Earlier, Finance Minister Arkhom Termpittayapaisith said the ministry would go ahead with its tax collection plan, saying this year was the right time to implement it.
"The Thai bourse has witnessed growth after being spared the adverse domestic economic impacts of the Covid-19 pandemic," he said.
He said ending the tax waiver on share sales should help expand Thailand's tax base and pull in additional revenue for national development.
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